The word hit has several meanings:

1. To strike something with force. You hit a baseball with a bat, or accidentally hit your thumb with a hammer. A boxer hits a punching bag during training. The force can be gentle or powerful: you might lightly hit a drum or forcefully hit a tennis ball over the net.
2. A success that many people enjoy. A hit song plays constantly on the radio because millions of people love it. A hit movie sells out theaters. A Broadway show becomes a hit when audiences keep coming back. The opposite is a flop, something that fails to attract an audience.
3. In baseball, when a batter safely reaches base after striking the ball into fair territory. A player with many hits in a season is having a great year. Baseball announcers might say a batter “got a hit” or “hit a single.”
4. To reach or affect something. Bad news can hit you hard emotionally. A snowstorm hits a city when it arrives. You hit a target when your arrow strikes it. You might hit a milestone birthday, like turning ten.

The phrase hit or miss means unpredictable: sometimes it works, sometimes it doesn't.