~N예요 / ~N이에요: to be (am, is, are)

이게 뭐예요? (=What is this?)
저게 뭐예요? (=What is that?)
며칠이에요? (=What's the date?)
얼마예요? (= How much is~?)
몇시예요? (=What time is it?)
'이에요/-예요' is attached to a noun with no space between them. ('-이에요' is used when a noun ends in a consonant and '-예요' when the noun ends in a vowel.)
'이게' is used to indicate an object that is close to the speaker.
'저게' is used to indicate an object that is far from both the listener and the speaker. Both of them are used only as the subject of a sentence.