Explain BMR to me like I’m a dummy

My understanding is it’s the calories needed if I was in a coma, barely functioning.

Asking because I’m only a couple weeks postpartum (not breastfeeding, so don’t need specific amount of calories) and barely moving my body until I am cleared for exercise at 6 weeks pp.

I’m trying to not gain during this time but I don’t care if I maintain. Should I be eating my BMR then?