This means that the enemy army considering killing David of greater worth than killing 10,000 of the other men. The number 10,000 here is an exaggeration used to emphasize a very great number of people. Alternate translation: "they would rather kill you than to kill 10,000 of us" or "killing you is worth more to them than killing a great number of us" (See: [[rc://en/ta/man/translate/figs-explicit]] and [[rc://en/ta/man/translate/figs-hyperbole]])
David could help them from the city by advising them and sending men to help them. This can be stated clearly. Alternate translation: "that you stay here in the city and send help to us" (See: [[rc://en/ta/man/translate/figs-explicit]])