Lose is a verb; it is the opposite of “win” and also the opposite of “find.”
▶️ The baseball team is losing 5-2.
▶️ I lost my favorite hat. I can’t find it anywhere!
Loose is an adjective, it is the opposite of “tight.”
▶️ These pants are too loose – I’ll need to wear a belt.
▶️ My seven-year-old daughter has a loose tooth; it will probably fall out soon.
In lose, the “s” sounds like a “z.” In loose, the “s” sounds like an “s.”