The word feint is linked with the word feign, which means "to give a false appearance to". Feinting involves pretending to move, pass, or shoot one way before doing something else.
Feinting a pass makes the whole defense jump in the wrong direction. The player guarding the ball handler will likely be faked out the most, and hopefully will be easy to move around. This is a great way to get a clear shot or walk through towards the basket.
Feinting a shot is useful too. If the ball handler fakes a shot, they can likely draw a block attempt from the defender. This can allow the ball handler to step around the defender or move the ball somewhere else.
Feinting a movement in one direction before heading in the other direction is the most common type of fake move. This usually will be utilized to open the route in the other direction. The ball handler can also feint a movement to open a pass or a shot.