Learn Hardcore Icelandic: Barnið fær snarl eftir skóla. - The child gets a snack after school.

Barn means child, while barnið means the child. Icelandic usually puts the definite article at the end of the noun instead of using a separate word like the. Here, -ið is the definite ending for this neuter singular noun.

Is barn always neuter, even if the child is a boy or a girl?

Yes. Barn is a grammatically neuter noun. In Icelandic, grammatical gender does not always match real-life sex or gender. So even if the child is a boy or a girl, the noun barn itself is still neuter. If you want to make that distinction clear, you would usually use a different noun such as drengur for boy or stelpa for girl.

Why is the verb fær and not fá?

Fá is the infinitive, meaning to get or to receive.
Fær is the present-tense form used with a third-person singular subject like barnið.

A few forms of fá are:

ég fæ = I get
þú færð = you get
hann / hún / það fær = he / she / it gets

So barnið fær means the child gets.