What do SQUATS actually do?

So I have a big bum as I am around 60kg. I want to lose fat around my hips and bum and thighs as I had a pear shaped body and it is the place where I gain most of my weight. Will squats make my bum more bigger or does it burn fat on my bum? I am really confused because before when I was a healthy weight I would do squats to lift my bum and get a better shape. I'm just really confused. Any help ?