To be reflected in a mirror; for an image or light to appear on a mirror's surface.
鏡に映る自分の姿をじっと見て、髪型を直した。
She looked closely at her reflection in the mirror and fixed her hair.
新しいドレスは鏡に映るとよく似合って見える。
The new dress looks especially good when seen in the mirror.
子どもの姿が鏡に映って、部屋で遊んでいるのが見えた。
I saw the child reflected in the mirror, playing in the room.