This is basically a precast for entity commands, will check the spawn you are using the entity command on to see if you can actually use the command. An example usage is a door that you can click on and highlights but can't be opened until an event or quest has been completed and before that happens it gives you a message saying you can't open the door
Spawn is the spawn the entity command is being used on
Player is the player using the command
Command is the name of the entity command