Stalemate Example: Black to move
Black can’t move here
Since his King will be captured (illegal move)
The same thing happens if Black moves here
His King will be captured (illegal move)
And Black can’t take White’s Rook either...
Since his King would be captured (illegal move)
Therefore Black has no legal moves
But his King is NOT in check (attacked)
Therefore the game is in a stalemate and ends in a draw