‘Whereabouts’ (always ends with an ‘s’) is both a noun and an adverb.
As a noun, it means the place where someone or something is. It can be used as singular or plural.
- I don’t know his whereabouts.
- The whereabouts of the car is/are unknown.
As an adverb, it is used to ask about the location of something (where).
- Whereabouts is your new home?
- Whereabouts did he get that?