Learn Polish: To jest dom. - This is a house.

When you introduce what something is ("This is a..."), Polish uses the fixed phrase to jest. You only need to worry about matching the gender if you are pointing out a specific object, like "This house is big" (Ten dom jest duży).

Where is the word for "a" in this sentence?

Polish doesn't have articles like "a", "an", or "the". The single word dom translates to "a house", "the house", or just "house" depending on the context.

Why is dom in its basic dictionary form here?

After the introductory phrase to jest, Polish uses the Nominative case. This is the basic, default form of a noun exactly as you find it in the dictionary, so dom doesn't need to change its ending here.

Can I leave out jest and just say To dom?

Yes! In everyday spoken Polish, people often drop the word jest and simply say To dom. Both are perfectly correct, but To jest dom is the full, standard way to write or say it.