The phrasal verb "stop" can be used in a variety of ways. Here are a few examples:
Stop by: To visit someone or a place briefly
Example: Can you stop by the store and pick up some milk on your way home?
Stop in: To visit someone or a place briefly
Example: I'm going to stop in and see my friend before I head home.
Stop off: To visit someone or a place briefly on the way to somewhere else
Example: I'm going to stop off at the post office before I head to work.
Stop out: To stay out late or not go home at the usual time
Example: I'm going to stop out with my friends tonight.
Stop over: To stay somewhere for a short time during a journey
Example: I'm going to stop over in Paris for a few days on my way to Rome.