What is a US fetal bio physical profile

I am 30w1d with my third pregnancy. For the first time I have GD, I am now having a US fetal biophysical w/o nst in 2 weeks, what should I expect? I read on google what’s the difference between that & a growth scan but I want to hear your experience. what does it focus on, will they still give you pictures? Should be I worried? I am feeling stressed about being considered high risk, I am also having weekly nst’s. I know it’s all for the baby’s well being and I rather have the peace of mind that baby is ok but feeling overwhelmed with what’s to come.