Learn German: Ein Drittel isst die Hälfte davon sofort. - A third eats half of it immediately.

In German, fractions are capitalized when they are used as standalone nouns. Since Ein Drittel (A third) is the subject of the sentence, it acts as a noun and gets a capital letter. Almost all fractional nouns end in -tel or -stel and are neuter (like das Drittel or das Viertel).

Why is it die Hälfte and not a neuter word like "das Halbtel"?

The word for "half" is a special case in German. While other fractions are predictably formed by adding -tel or -stel to the number (like drei becoming Drittel), "the half" is always the feminine noun die Hälfte.

Since "a third" usually implies a group of people, why is the verb isst in the singular?

Even though Ein Drittel might refer to multiple people in reality, the grammatical subject itself is singular (one single third). Therefore, the verb must take the third-person singular form: isst.

How does davon mean "of it" in this sentence?

davon is a "da-compound," which combines da- (there) and von (of/from). Instead of saying "von es" (which is grammatically incorrect when referring to objects or concepts), German uses davon to refer back to whatever the whole amount was.