Commands that support the time argument allow you to specify how long something will last or how long something will take. For example, you may want to move two objects the same distance but have one of them take 10 seconds longer than the other to get where it's going, or you may want a particular rotation to last only 3 seconds so that the rotated object will stop in a specific position.
In the case of the light command, the time argument specifies the interval in seconds for the blink, pulse, fadein, and fadeout effects.
create light color=red brightness=3 fx=pulse time=5
create move -1 0 0 loop time=5 wait=3
create move 0 50 0 loop time=10 reset
activate rotate -9 time=1.6 wait=5.4; bump rotate -36 time=4 wait=7