Learn Hardcore Croatian: Mi imamo veliku kuću.

Mi means “we” and serves as the subject pronoun. In Croatian the verb ending (-mo in imamo) already indicates first person plural, so you can drop Mi for a neutral statement.
Example without pronoun: Imamo veliku kuću.

What is the role of imamo in this sentence?

Imamo is the first person plural present tense of the verb imati (“to have”). Together with the implied subject mi, (Mi) imamo means “we have.”

Why is kuću in this form, not kuća?

Kuću is the feminine singular accusative of kuća (“house”), used because it’s the direct object of imamo. In Croatian, direct objects take the accusative case.

Why does the adjective appear as veliku instead of velik or velika?

Adjectives must agree with the noun in gender, number, and case. Since kuću is feminine singular accusative, velik (“big”) becomes veliku in the same form.

How do you express “Do we have a big house?” as a question in Croatian?

Invert the verb and add the enclitic question particle -li:
Imamo li veliku kuću?

Croatian has no words for “a” or “the.” How do you know which the speaker means?

Croatian doesn’t use articles. Context usually tells you if it’s definite or indefinite.
Imamo veliku kuću could be “We have a big house,” “We have the big house,” or simply a statement about owning a big house.

Can you change the word order in Mi imamo veliku kuću?

Yes, Croatian allows flexible word order for emphasis. The neutral order is SVO (Subject-Verb-Object): Mi imamo veliku kuću.
To emphasize “big,” you might say Veliku kuću imamo. Placing the adjective-noun pair first highlights the size of the house.

How do you pronounce kuću, especially the letter ć?

Ć is a soft “ch” sound, like the beginning of English “chew” but lighter.
Pronunciation: [ˈku-t͡ɕu], roughly “KOO-choo.”