Learn Italian: Quell'albergo là è chiuso, ma questo è aperto. - That hotel there is closed, but this one is open.

The word quello changes its ending to match the noun that follows it, using the exact same rules as the words for "the". Because you would say l'albergo (the hotel) since it starts with a vowel, quello drops its final letter and adds an apostrophe to become quell'.

Why is là used after quell'albergo? Doesn't quell' already mean "that"?

Yes, quell' means "that", but Italians often add là or lì (both mean "there") after the noun for extra emphasis. It is just like saying "that hotel over there" in English.

Why does the second half of the sentence just say questo without a word for "one"?

In English, we often say "this one" or "that one" to avoid sounding incomplete. In Italian, pointing words like questo (this) can stand perfectly on their own as pronouns. You never need to add a word for "one" in these situations!

Why do the words chiuso and aperto end in -o?

These words mean "closed" and "open", and they are acting as adjectives describing the hotel (albergo). Since albergo is a masculine singular noun, the adjectives must match it by taking the standard masculine singular -o ending.