Is has subject noun

No, the Word 'has' is a verb; the third person, singular of the verb to have.

The verb 'has' can function as a main verb or an auxiliary verb.

Examples:

Junior has a cold. (main verb)

Junior has been to the doctor. (auxiliary verb)

A noun is a Word for a person, a place, or a thing.

The noun 'Junior' is a Word for a person, the subject of both sentences.

The noun 'cold', is a Word for a thing, the direct object of the verb 'has'.

The noun 'doctor' is a Word for a person, the direct object of the verb 'has been'.