It’s super simple!

You click a square, it’s either a bomb or not. If it’s not, it will show a number telling you how many of the surrounding 8 squares contain a bomb. If a square has 0 bombs in surrounding squares it will just open, so you save unnecessary clicks. It’s the goal to click every square that does not contain a bomb. If you click a bomb, you lose.

After understanding the rules you can beat the game super quick and easily.