Lose, with only one 'o':
Verb. To stop having something you had before, with a negative connotation. To not have success at game or competition.
Dictionary entry: https://dictionary.cambridge.org/dictionary/english/lose

Loose, with two 'o's:
Adjective. It can mean the oposite of either "tight", "attached" or "controlled". It can also be a verb, and in that case it means something similar to "let loose".
Dictionary entry: https://dictionary.cambridge.org/dictionary/english/loose