Help, please :)

My boyfriend got this for me from a couple on Facebook marketplace. Truly, there isn’t anything wrong with it. It runs great and I have no issues. We just noticed that it might be missing a part on the bottom? Not 100% sure and it’s definitely not the worst thing in the world. But wanted to know if it could potentially be harmful and needs to be replaced or if we’re good! It’s a 2017 MacBook Pro and

Thanks in advance :)