The following's a scene I saw in a movie. Could you explain to me what does "I'm in your corner" mean? Idiom? Is that mean encouragement? Or same as "You're covered, I got your back"?

A woman enters the office for her interview. Two men were in the room. The interviewer sat behind his desk, listening the other guy reporting something to him. When finished, the guy walked out, and while passing the woman, he nodded encouragingly. Obviously he knew her. And he said to her, "I'm in your corner," and then walked out of the office.
Full Member194

It's mainly encouragement, plus the idea that I support your opinion or action.

It comes from boxing, where the people who help the boxer at the end of each round are located near his corner of the boxing ring.

Veteran Member79,198
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I'm in your corner simply means I'm on your side. Like in the boxing ring, when the boxer's supporters are 'in his corner', ready to offer words of encouragement between rounds, to wipe his brow and send him back our whilst cheering him on. We all need at least one person who we can totally rely upon to be in our corner.
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It means "I'm in support of you" or in some other cases "I'm your ally" (I'm on your side).