But  - The Greek word translated as "but" joins phrases in an adversarial way. However, it also can be used to mean "if" and "so." Looking at the previous verse, Matthew 9:12, "so" seems more appropriate than "but." Since the word almost always falls in the second position, translating it as "however" often captures its feeling.

go  - (WF) It is not in the form of a command, nor is it in the second person ("ye"). The term also isn't the common verb almost always translated as "go" in the NT. In its active form, this word means "to lead over," "depart," and "to carry over." This word, however, uniquely means both "to pursue a course" and "to depart from life."

ye -- This is from the second-person, plural form of the verb.

and -- (IW) There is nothing that can be translated as "and" in the Greek source. It is added because the previous verb was made active.

learn  - "Learn" is the active verb here. It means "to learn from study or by practice" or "acquired the habit." It is not from the most common Greek verb that means "to learn." It is not in the form of a command, but an active verb. It is not the past, present, or future, but a tense that indicates something happening at a specific point in time.

what  - There word translated as "what" means "anything" "something," "someone," or "anyone." In questions, it means "what." It is the object of the verb "learn." This use of this word often, but not always, indicates a question. The original Greek does not have any punctuation marks, so words like this are clues to phrasing.

that - -- (IW) There is nothing that can be translated as "that" in the Greek source.

meaneth,  -  (WW) The verb translated as "meaneth" is the common form of the verb "to be" or, in this form "it is." When the verb "to be" appears early in the sentence before the subject, the sense is more like "it is" or, in the plural, "there are." (Note: punctuation was not part of the original text but added centuries later.)

I -- This is from the first-person, singular form of the verb.

will  - (CW)  The Greek word translated as "will" expresses consent and even a delight in doing something not the future tense as in English. In the original Hebrew of Hosea, "will" or "desire" is from chaphets, which means "to delight in," "to take pleasure in," and "to be pleased with." 

have -- (IW) There is nothing that can be translated as "have" in the Greek source.

mercy,  - The Greek term translated as "mercy" means "good will toward the afflicted." It also means "pity" and "compassion." In the original Hebrew, "mercy" is checed, which means "goodness," "kindness," and "faithfulness." It also means "to be ashamed" and "a reproach." Based on the verb checed ("to be kind"), the adjective combines both the idea of being good and feel guilty if you are not good. It the Greek Septuagint version, this word is in the dual masculine form (referring to Ephraim and Judah), but Christ changes it, putting it in the simple neutral form.

and  - The Greek word translated as "and" here is used as the conjunction "and."

not  - The Greek word translated as "not" is the Greek negative used to deny objective facts, not opinions. It makes a negative statement of fact. Adding "really" often captures its feeling better than "no" or "not" alone.

sacrifice:  - Interesting, the Greek terms translated as "sacrifice," does not refer to the act of sacrifice but to "a burnt offering" or "victim." In Hebrew, "sacrifice" is zebach, ("a sacrifice") which is the noun form of zabach, which means "to slaughter" either for sacrifice or for eating.

for  - The word translated as "for" can be treated as supporting a dependent clause, or, in written English, as "this is why..." to start a new sentence.

I -- This is from the first-person, singular form of the verb.

am -- (CW) This helping verb indicates the present tense of the verb, but the verb is not the present tense, but a tense that indicates something that happened at a specific point in time, past, present, or future. 

not   - The Greek word translated as "not" is the Greek negative used to deny objective facts, not opinions. It makes a negative statement of fact. Adding "really" often captures its feeling better than "no" or "not" alone.

come  - The word translated as "I am come" primarily means "to start out." It indicates movement, especially its beginning, without indicating a direction toward or away from anything, so it works either as "start," "come," or "go," but it is more like our phrase "being underway."

to -- This "to" is added because the infinitive form of the verb requires a "to" in English.

call  - The term translated as "call" is like our word "call" means both "to summon" and also "to name."

the -- There is no Greek article "the" here in the source, but the noun is plural and in English an article is used before plural nouns in phrases like this.

righteous,  - The term translated as "righteous" means "those who observe the laws," "well-balanced," and "meet and fitting."  Since it is plural, masculine, it refers to a group of individuals, "law-abiding ones."

but  - The Greek word translated as "but" denote an exception or simple opposition. "Still" or "however" work well when the word isn't being used as a conjunction, especially when it begins a sentence.

sinners  - - (WW) "Sinners" is a Greek word that means "mistaken," "erroneous" or "erring." It also means "of bad character" but with the sense of being a slave or low-born not evil. Only in biblical translations is this term given the sense of wickedness. More about the translation issues regarding "sin" in this article here. Since it is plural, masculine, it refers to a group of individuals, "mistaken ones."

to repentance. -- (OS) There is nothing that can be translated as "to repentance" in the Greek source.