are three examples of territory surrounded by six White stones.
In Diagram 1, the stones and sides at the corner of the board make 9 points of territory. Note that while the spaces on the edge of the board act as borders, because they are empty they also are counted as points.
Diagram 2, the stones at the side of the board enclose 4 points
In Diagram 3, the stones surround 2 points of territory in the middle of the board.
are two examples of finished games. The game is finished when all the
empty points are surrounded by one player or the other.
In Diagram 4, Black surrounds 16 points and White surrounds 17 points, so White wins by 1 point.
In Diagram 5, Black has 16 points while White has 11, so Black wins by 5 points.
Note that placing a stone inside territory you have already surrounded would reduce your score by a point.