XはYをほしがっている as “X wants Y”
As touched upon earlier, it can be construed as impolite to ask about a person’s wants. Even more so, it is considered considerably impolite to state a person’s wants for them; because of this, in lieu of the grammatical construct がほしい, ほしがっている is used when referring to a third-person subject’s wants. ほしがっているconveys the idea that the subject is showing signs of such wants as opposed to the idea that the subject directly feels that way. In contrast to ほしい, ほしがっている is a verb and acts as such in sentence construction. More specifically, the Dictionary Form, ほしがる is a verb and いる is another verb of itself, and together they make the connected form ほしがっている. As a result of this, the particle used in conjunction with ほしがっている is を as opposed to the particle が used with ほしい.
Kanojo wa nomimono wo hoshigatte iru.
(She wants something to drink.)
Kodomotachi wa yasai deha naku niku wo hoshigatte imashita.
(The children wanted meat instead of vegetables.)