"they will grab you." This expression refers to people exercising authority over the disciples. Alternate translation: "they will arrest you" (See: [[rc://en/ta/man/translate/figs-metonymy]])
The word "synagogues" is a metonym for the people in the synagogues, specifically the leaders. Alternate translation: "giving you over to the leaders of the synagogues" or "taking you to the synagogues so that the people there can do to you whatever they want to do" (See: [[rc://en/ta/man/translate/figs-metonymy]])
The word "name" is here used to refer to Jesus himself. Alternate translation: "because of me" or "because you follow me" (See: [[rc://en/ta/man/translate/figs-metonymy]])