Learn Croatian: Kuće su velike, a sobe su čiste. - The houses are big, and the rooms are clean.

Both kuća (house) and soba (room) are regular feminine nouns that end in -a in their singular dictionary form. To make them plural, you simply change that -a to an -e. So, kuća becomes kuće and soba becomes sobe.

Do the adjectives velike and čiste also end in -e for the same reason?

Exactly! In Croatian, adjectives must match the noun they describe in gender, number, and case. Since kuće and sobe are feminine plural nouns, the adjectives velik (big) and čist (clean) take the feminine plural ending, which is also -e.

The translation says "and", so why does the sentence use a instead of i?

While i simply connects items in a list (like "apples and oranges"), a is used to connect two different thoughts, compare things, or introduce a slight contrast. Here, you are comparing two different subjects (the houses vs. the rooms), so a is the natural choice. It usually translates as "and", "but", or "while".

Why do we need the word su twice in this sentence?