To jest mój pierwszy dom.

In Polish, the phrase To jest… (“This is…”) is a fixed identifying construction. Here to is a neuter singular pronoun that doesn’t change to agree with the gender or number of the noun that follows. You always say To jest regardless of whether you’re pointing at a man, a house or a group of people.

Key points:
• To = “this/it” (neuter, uninflected in this structure)
• Ten, ta, ci are demonstrative adjectives, not the standard pronoun used in To jest…

jest is simply the third person singular present tense of the verb być (“to be”), i.e. he/she/it is. In To jest…, jest links the pronoun to with what follows, functioning like the English is in “This is…”

After to jest the noun behaves as a subject complement, not a direct object. Polish treats both sides of to jest like two equals, so the noun remains in the nominative.

Compare:
• “To jest dom.” → dom (nom.)
• “Widzę dom.” → domu (genative) or dom (accusative) depending on context

mój is the first‐person singular possessive pronoun in nominative masculine singular, agreeing with dom (which is a masculine noun). Polish possessive pronouns change to match the gender, number and case of the noun they modify, not the gender of the speaker.

Forms of “my” in nominative:
• masculine nouns → mój
• feminine nouns → moja
• neuter nouns → moje
• plural → moi / moje

pierwszy is an ordinal number (“first”) used as an adjective, so it follows the normal Polish adjective–noun order (adjective + noun). It agrees in gender, number and case with dom (masculine singular nominative).

Forms of pierwszy in nominative:
• masculine singular → pierwszy
• feminine singular → pierwsza
• neuter singular → pierwsze
• plural → pierwsi / pierwsze

Yes. Polish has no indefinite or definite articles. Nouns stand alone, and context or additional words (like possessive pronouns or demonstratives) convey definiteness or indefiniteness. E.g.:
• To jest dom. → “This is a/the house.” (context tells you)
• To jest mój dom. → “This is my house.”

No. In an identification sentence you need the pronoun to as the subject. Simply saying Jest mój pierwszy dom would sound ungrammatical or like you’re missing a subject. If you want to change the meaning to “I have my first house,” you’d say Mam mój pierwszy dom, using mam (“I have”) instead of to jest.