Is pizza a countable noun or an uncountable noun? I don't understand the answer of askedex. Who can give a more detailed answer?

Is pizza a countable noun or an uncountable noun? I don't understand the answer of askedex. Who can give a more detailed answer?

In spoken language, we can say "pizza", but in written language, it is an uncountable noun. It needs to be connected with a quantifier to express quantity, such as a piece of pizza
I hope my answer can satisfy you``