Here the "heart" represents a person's thoughts and true feelings. AT: "my thoughts" or "my inner feelings" (See: [[rc://en/ta/man/translate/figs-metonymy]])
Here Jeremiah asks Yahweh to prepare to punish the wicked as if they were sheep to be taken away to be slaughtered. AT: "Take the wicked people away, like sheep for slaughter" or "Prepare to punish those wicked people" (See: [[rc://en/ta/man/translate/figs-metaphor]])