Here "Now" is used to mark a break in the main story line. Here Matthew tells background information about Judas and the signal he planned to use to betray Jesus. (See: [[rc://en/ta/man/jit/writing-background]])
This direct quotation can be stated as an indirect quotation. Alternate translation: "saying that the one he kissed was the one they should seize." (See: [[rc://en/ta/man/jit/figs-quotations]])