Same as a Battery Switch?

I am a little new to boating so bear with me. I have this onboard charging box in my boat and am wondering if it the same as a battery switch or similar. Yesterday we would stop and play music (Just a sony deck no amps) and a couple times it was hard to start. When I tried to fast throttle start it, it wouldnt even turn over. I do have a couple batteries in it running so I was wondering why all the potential battery drain. I am inculding a pic so you can see what it is I am talking about. Thanks

It appears you have some type of priority charging system that is probably automatic in nature( I am not familiar with that brand). It is not the same as a battery switch which is a mechanical switch that has to be manually changed by an external input such as a person.
These types of switches are often the source of problems but if properly utilized they are great. Remove it from the system, if the problem goes away then that might help you figure out the issue.

Still curious to see if anyone knows what this may be. A battery tender maybe. Just want to know if this will funtion the same as a battery seperator or combiner.

It looks like an isolator. They are used to charge both batteries when the engine is running and separate them when not running. Start by testing both batteries then check the wiring and make sure the radio is not connected to the starting battery.

Everything is connected to the starting battery. That's why I want to know if everything is innerlinked before I move wires. The boat used to be used for fishing and had a trolling motor so I thought maybe it was a charger for that since it can have 2 more batterys wired to it.