Is sees singular or plural

Answer 1

The word 'sees' is a verb, the third person, singular present of the verb to see. Example:

He sees his mistake.

If you're talking about the Holy See, there is no plural, since it is unique, although it could be used as a possessive, as in "the See's main purpose..."

Answer 2

"Sees" is the third person singular form of the verb "see." It is used when referring to one person or thing observing or perceiving something.