The Sun is a big ball of gas. It is massive. Gravity is wanting to pull it inwards.
So, why doesn't the Sun collapse into a teeny, tiny ball?
What force balances the pull of gravity? Pressure.
Gravity pulls in, pressure pushes out. This force balance is called Hydrostatic Equilibrium.
Hydrostatic Equilibrium applies
in many places. You have experienced hydrostatic equilibrium throughout
your life, in many situations.