"Now" introduces background information that Jesus and the Jewish authorities understood.
## what do you say about her? ##
This can also be translated as a command. "So you tell us. What should we do about her?"
## to trap him ##
"to trick him." This means to use a trick question.
## so that they might have something to accuse him about ##
What they would accuse him of can be made explicit: "so that they could accuse him of saying something wrong" or "so that they could accuse him of not obeying the law of Moses or not obeying the Roman law." (See: [[rc://en/ta/man/translate/figs-explicit]])