An Object is normally a noun, pronoun or noun phrase that comes straight after the verb, and shows what the verb is acting upon.
- Year 2 designed puppets. [noun acting as Object]
- I like that. [pronoun acting as object]
- Some people suggested a pretty display. [noun phrase acting as Object]
Objects can be turned into the Subject of a passive verb, and cannot be adjectives (contrast with Complement).
- A display was suggested. [Object of active verb becomes the Subject of the passive verb]
- *Year 2 designed pretty. [incorrect, because adjectives cannot be objects]
Note that Object is a function label which covers two different types: Direct Object and Indirect Object (and some other units typically selected by verbs).