So basically
In minesweeper, when you click a tile, there will be a number. That number will be the probability of a mine exploding. There are 8 tiles surrounding said tile that could be a mine.
For example, a 1 tile. Upon clicking a 1 tile, if no other tiles reveal themselves, the tiles surrounding the 1 tile has a 1/8 chance of exploding. This chance goes down as more tiles are revealed.
If a 1-tile has only one uncovered tile in its proximity, that tile is a mine and should be flagged. Same goes with 2 to 8 tiles.
In order to win the game, you have to uncover every tile that isn't a mine. You have a limited amount of flags for the amount of mines that there are supposed to be.