Can this also be used for (The) Red Square in Moscow?
That would be 'Y Sgwâr Coch' since it is a name of a place rather than a description of an object.
I was aware of the "y" - therefore i put my "the" in parentheses; i was just wondering if "square" (object) and "square" (place) are the same in welsh like in english (since they aren't in my mothertongue)
Yes very much so. A central part of a town or village can be referred to as 'Y Sgwâr' (The Square) and 'sgwâr' is the name of the shape.
I assume so.