A person who sings, especially as a performer or profession. Neutral and widely used for pop, classical, and other kinds of singers.
She is a famous singer.
I bought that singer's new album.
She says she wants to become a singer in the future.
He debuted as a singer in his teens.
He moved to Tokyo aiming to become a singer.
歌手 specifically means a singer, a narrower category than ミュージシャン which also includes instrumentalists and composers.
enka singer; singer of Japanese traditional ballads
alto singer; alto voice