"Bilasáana"

Translation: Apple

[DrRansom]

Could someone explain the plural form (apple/s)?

[Judorange123]

No distinction in number in Navajo besides a few nouns referring to people ("boy, girl, man, woman,... "). Plurality can be inferred from conjugation (plural da-, seriative hi-, iterative mode, distributive aspect,...).

[WestpointCali]

Serious question: is this used to reference the company Apple?

[_XeNoX]

Well, it's just how you say apple in navajo. If you are talking about the company, even if Navajo, you would write 'Apple'.