The phrase "to finish off" means to complete or end something in a decisive manner. It can be used both literally and figuratively, depending on the context in which it is being used. For example, if someone says they are going to finish off their meal with dessert, they mean that they will eat dessert after finishing their main course. On the other hand, if a person says they finished off an opponent in a boxing match, they mean they defeated them decisively. In summary, "to finish off" means to bring something to its conclusion or put an end to it completely and definitively.