Xがほしいです as “(I/We) want X” or Xがほしいですか as “Do you want X?”
The い-adjective ほしい is used to express a desire. Despite being an い-adjective and being conjugated as such, ほしい’s structural use is more similar to that of a verb.
Watashi wa inu ga hoshii desu.
(I want a dog.)
Cake ga hoshii desu.
(I want cake.)
Inu ga hoshikatta desuga ima neko ga hoshii desu.
(I wanted a dog before but now I want a cat.)
Sore wa hoshiku arimasendeshita.
(I did not want that.)
Ittai nanika ga hoshii ka darouka?
(What on earth do you want?/Just what is it exactly that you want!?)
*Notice that when no subject is explicitly stated, it is implied to be the speaker unless the sentence is a question, in which the implied subject is the addressee.
*The question form of this construct can at times be construed by addressees as much too assertive speech, so it is best to be careful in using this construct when speaking to people who should or must be shown respect.