The KJV does its best to translate this line, while most other Biblical versions seek to interpret it. The common interpretation is that it means that this results in an opportunity to give testimony. However, that idea would have been expressed more clearly in other words. The words here seem purposefully vague, with many possible meanings. It starts with a unique word with a lot of different meanings.

There is no "and" in the Greek we use today.

"It shall turn" is a verb that literatlly means to " step off from". It is a word used uniquely here. The meaning  depends on what the subject is since it could refer to either the various calamities in preceding verses or the final one of being taken to kings and governors.  It is used most commonly to mean "disembark", and "go away". However, of events it means "result from", "turn out". When no adjective is used, the sense is positive, "turn out well". The form of this verb can be either the future tense or something that possibly happens. You may notice that verbs that have this dual form, most do not, seem to have been used throughout this section of prophecy.  Jesus's desire to use the fight form often determines his use of uncommon verbs.

The Greek pronoun "you" here is plural.  This form is used for nine different purposes. The dative case has several uses in ancient Greek 1) the indirect object of an action ("Matthew gave his Gospel...to all.") 2) the instrumental dative ("Matthew wrote...with a pen.") 3) the location (in time or place) dative (...in Judea.") 4) to declare a purpose (]..as a testimony"), 5) a benefit ( "...for our benefit"); 6) possession ("...of his own") 7) an agent ("...by himself") and 8) a comparison ("...as the longest") 9) area of affect ("in the sphere of men"). The question is which of these roles does this form play here? Several are possible.

The word translated as "for" is also used in an uncommon way.The most common use of this preposition is to mean "into (of place)." The most likely meanings are "in regard to" (to express relation) and "for" (of purpose or object).

The only simple word here is the final one, "testimony" which is the Greek word for "testimony" or "proof."  It the "it"