How do you say Dutch English? It's Holland; ; Netherlands; Netherlands; Square head or Holland?

The full name of the Netherlands is Kingdom of the Netherlands (translated as "Kingdom of the Netherlands");

Generally speaking, it is more common to add the before the Netherlands, because the Netherlands cannot be used alone, and the Netherlands (translated as "Netherlands") is the most common and simple statement;

Holland is an informal/habitual way to express the country "Holland", because the Netherlands was originally composed of two provinces, North Holland and South Holland, and the Netherlands, as a general term for these two provinces, has been used until today. But now the Netherlands actually refers to a region in the west of the Netherlands, not the whole Netherlands.

Squarehead refers to a kind of people, that is, Germanic immigrants, which include Germans, Dutch and so on. And the scope is more general, not specifically Dutch.

Dutch is simply "Dutch" or "Dutch".