Learn Polish: Moje rodzeństwo mieszka daleko.

In Polish, rodzeństwo (siblings) is a collective noun. Even though it refers to multiple people in real life, grammatically it is a singular neuter noun. That is why it takes the third-person singular verb mieszka (lives) instead of the plural mieszkają.

Because rodzeństwo is neuter singular, is that why we use Moje?

Exactly. Moje is the neuter singular form of the word "my". It matches the grammatical gender of rodzeństwo (which ends in -o, a common ending for neuter nouns). If it were a masculine noun, it would be Mój, and if feminine, Moja.

Can I use rodzeństwo to mean just one sibling?

No, rodzeństwo always refers to siblings as a group. Polish does not have a common, everyday word for just one "sibling". To talk about a single sibling, you simply specify if it is a brother (brat) or a sister (siostra).

What type of word is daleko?

It is an adverb meaning "far" or "far away". In Polish, many adverbs are formed by adding -o to the root of an adjective. It modifies the verb mieszka to tell us where the siblings live.