Learn Hardcore Hausa: Ruwa ya fi abinci amfani. - Water is more useful than food.

First mention: include the full noun ( ruwa ).
Later mentions: you can safely use just ya ( it ), as long as there is no ambiguity about what ya refers to.

In Hausa, when a full noun is the subject, you almost always also add a short subject pronoun before the verb. This is called subject agreement or concord.

ruwa = water (noun, subject)
ya = he/it (3rd person masculine singular subject pronoun)
fi = to surpass, to be more than (verb)

So the structure is:

[Noun subject] + [subject pronoun] + [verb]
ruwa ya fi … = water it-surpasses …

You cannot say *Ruwa fi abinci amfani; without ya, the verb fi would have no subject marker, and the sentence is ungrammatical in standard Hausa.

But ya usually means “he”. Why is “he” used for ruwa (water)?