The original Wii Sports includes five sports.
Nintendo’s Wii Sports contains tennis, baseball, bowling, golf, and boxing. The compilation was designed to demonstrate the Wii Remote’s motion controls, allowing players to swing, roll, or punch through relatively simple physical gestures.
The game was bundled with the Wii in most territories and became one of Nintendo’s most widely played titles. Its accessible controls helped introduce people who did not typically play video games to console gaming. Each sport uses a different interpretation of the Wii Remote: tennis uses swinging motions, bowling uses a release gesture, and boxing uses two controllers for punches.
Wii Sports Resort is a separate sequel and should not be counted when answering this question. It added activities such as swordplay, wakeboarding, and archery. The original compilation has exactly five sports, making “five” the specific answer.