One timer

In ice hockey, a one timer is a shot that occurs when a player meets a teammate's pass with an immediate slapshot, without any attempt to control the puck on his stick. An effective one timer requires precise timing on the part of both players involved, especially the shooter. This play often results in a good chance at a goal. A wrist shot can also be done on a one-timer, though the puck is released far slower than a slapshot one-timer.

The effectiveness of the one timer comes from three things:

Greater angle, change of direction and/or speed increases the chances of the puck going into the net. Lesser angle, change of direction and/or speed decreases the chance of the puck going into the net.

Either way, the one-timer enjoys a greater success rate than a one-on-one shot between shooter and goalie.

The reason it is called a one timer is because the player only has one time to connect.

...
Wikipedia