This resolution says that if U.S. military forces are currently involved in combat in or against Cuba without Congress having formally voted to authorize that combat or declare war, the President must pull those troops out. It's built on the idea that Congress, not just the President alone, is supposed to sign off before the country goes to war somewhere. There are a few carve-outs, though: U.S. forces could still act to defend against an actual attack, respond to a clear and imminent threat of attack, or carry out operations aimed at stopping illegal drug trafficking, without needing separate congressional approval for those specific actions.