What does 1 Kings 22:4 mean?

He asked Jehoshaphat, 'Will you go with me to fight for Ramoth-Gilead?' Jehoshaphat answered, 'I'm with you all the way—my people and horses are yours.' 1 Kings 22:4 - Modern Text Bible

(Ahab asks for Jehoshaphat's help in battle, and Jehoshaphat agrees to support him.)