In a not very dense field you'll find many 1s because the mines will usually be spaced apart from one another.
The numbers indicate the number of mines neighboring that cell. Each cell is surrounded by 9 other cells so cells can be a mine, a blank or a number 1-9 indicating how many mines surround it.
I've played some advanced boards that are dense with mines and you see a lot more of the higher numbers.
Anyway with enough information you can deduce where certain mines are.
One thing I dislike about the game is you may encounter one or more areas that are a coin flip 50-50 shot that the mine is either here or there. Sort of sucks to rock a board only to lose in the final stretch because of something you have no control over.