上手　～ skillful　～　私は日本語が上手になりたい　～　I wanna become good at Japanese. よく　～　 often　　～　私は日本語をよく勉強しています　～　I often study Japanese.　　 If you mean 良く　～　well、　良く寝た　～　I slept well 良く　Is conjugation of 良い　　Which you can also conjugate into negative　良くない　～　Not good　And so on...