What kind of cooling system is my 2003 ford escape V6? Open or closed?

I have an old 2003 Ford Escape V6 engine. My car has been overheating for
a few weeks. It was leaking out of the right side of my car by the thermostat.
My grandpa has replaced the thermostat (we dont know if that was the issue)
and my car is still overheating. I do not see a radiator cap on top of my
radiator, but i believe i could have air in my system but dont know where let
alone if i have a radiator cap to be able to burp my system. Today after it
overheated on my way home i noticed i am no longer leaking but the hose
that goes into the top of my reservoir was putting liquid back into the
reservoir and making a gurgling sound. Idk if this is normal. please help me. i
have no idea what could be wrong or what to even check. My grandpa is
running out of ideas too.