kamhagh wrote:I was wondering why does it have multiple Ground pins:?
aren't all grounds supposed to be connected? is this for the current? I see the same thing on PC's PSU connector's for example my graphic's card power has (3 i guess) GNDs, why is it like that?
All grounds connect to the same point so only one is needed. The GPIO header contains several grounds mostly for convenience. You could have several circuits attached to the RPi and each would need to have a ground connection. Also it can cause problems in if one ground is looped from circuit to circuit.
Multiple grounds in your computer PSU are there to share the load so that one wire does not have to carry all the current. If too much current is allowed then the wire will get hot a possibly burn up.
Unless specified otherwise my response is based on the latest and fully updated Raspbian Buster w/ Desktop OS.