as a noun, 'extra' refers to something that is additional or supplementary, often beyond what is usual or necessary.
I bought a few extras in case we have more guests.
She worked as an extra in a Hollywood movie.
No extras are included with the base price of the car.
when referring to a person in a film, 'extra' often implies a background character with no speaking lines.
as an adjective, 'extra' describes something that is added to an existing or usual amount or number. It can also indicate something that is more than what is usual or necessary.
I'll have an extra slice of cake.
She always carries an extra pen.
They ordered the extra large pizza.
'extra' as an adjective often precedes the noun it modifies.
as an adverb, 'extra' means to a greater extent than usual or especially.
The cake was extra sweet.
He's been working extra hard for the upcoming exam.
when used as an adverb, 'extra' doesn't modify a noun directly. Instead, it modifies an adjective or another adverb, emphasizing the degree or extent.