* Adverb: "The lights went off." (Describes the verb "went")
* Preposition: "The dog ran off the porch." (Indicates direction or location)
* Adjective: "He had an off day at work." (Describes a noun, "day")
* Interjection: "Off you go!" (Expresses emotion or a command)
To determine the part of speech, you need to see the sentence it's used in.