'좋아해' is a casual form of '좋아해요'. You can use casual form to your friend or someone who is younger than you are.

The dictionary form of '좋아해' is '좋아하다' which means 'to like someone or something'.

If you hear someone says '좋아해', it could mean "I like you (or someone or something)." when the object is obvious in the situation.

Objects are commonly omitted in daily conversation when they are obvious.

The negation of '좋아해' is '안 좋아해 (don't like someone or something)' or '싫어해 (to dislike someone or something)'.

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