[RayVoy]

I can't find any info on it; but guessing it's for trailer lights.
However, the wire colours that I can see are not trailer light colours.

Could you provide the wire colours going to the connector?

 

[RayVoy]

It is not trailer connection. That what I thought first

Nope, it's not the right colours.

Do you have a volt meter?

 

[RayVoy]

The green has 12V

I assume your saying 12v with key out?

Ok, use you meter on the other wires, one at a time.
Turn on key, any of the other wires have 12v?
Try the brakes, check for voltage.
Try the lights, check for voltage.

Etc, keep turning things on, something will give you voltage and then you know the circuit it's connected to.