what is a subject noun for July?

The Word 'July' is a noun, a proper noun, the name of a specific month, a Word for a thing.

The noun 'July' functions as the subject of a sentence or a clause, and as the object of a verb or a preposition.

Examples:

July is the month that we usually take our vacation. (subject of the sentence)

The heat that July brings is quite intense in this region. (subject of the relative clause)

We have July off every year. (direct object of the verb 'have')

The renovations are scheduled for July. (object of the preposition 'for')