en_tn/1ki/12/27.md

If these people go up

The words "these people" refer to the people of the northern ten tribes of Israel.

the heart of these people

"Heart" here is a metonym for the people's allegiance and affection. AT: "the allegiance of these people" (See: rc://en/ta/man/translate/figs-metonymy)

turn again to their master, to Rehoboam king of Judah ... return to Rehoboam king of Judah

These phrases mean basically the same thing and are combined to emphasize Jeroboam's fear that the people would turn again to Rehoboam as king. (See: rc://en/ta/man/translate/figs-parallelism)