Learn Croatian: Ulice su stare, a zgrade su nove. - The streets are old, and the buildings are new.

Both ulica (street) and zgrada (building) are feminine nouns, which usually end in -a in the singular. To make a regular feminine noun plural when it is the subject of the sentence, you change that -a to -e. So, ulica becomes ulice and zgrada becomes zgrade.

Why do the adjectives stare and nove also end in -e?

In Croatian, adjectives must match the noun they describe in both gender and number. Because ulice and zgrade are feminine plural nouns, the adjectives describing them must take the feminine plural ending, which is also -e.

Why is the word for "and" here a instead of i?

While both i and a can translate to "and", a is used to show a contrast or a shift in focus, similar to "while" or "but" in English. Because the sentence contrasts old streets with new buildings, a is the correct word to link them.

Could I leave out the second su?