退后(tuì hòu) - to step back, to move back, to retreat in Mandarin

退后 (tuì hòu) means to move backwards physically. It is common as a bare command at an accident, a fire or a police cordon, which is why subtitles are full of it: 退后 on its own is Stand back.

It takes a quantity after it rather than before: 退后一点 (back up a bit), 退后两步 (two steps back), 退后几米. For the polite version put 请 in front and 一点 on the end.

Do not stretch it into the figurative senses English gives step back. Withdrawing from a job or a contest is 退出, falling behind in progress is 落后, and taking a mental step back to reconsider is 冷静一下 or 重新考虑. 退后 keeps its feet on the ground.