A past participle
indicates past or completed action or time. It is often called the 'ed' form as it is formed by adding d or ed, to the base form of regular verbs, however it is also formed in various other ways for irregular verbs.
It can be used to form a verb phrase as part of the present perfect tense.
For example:-
It can be used to form the passive voice.
For example:-
It can also be used as an adjective.
For example:-
It can be used to form a verb phrase as part of the present perfect tense.
For example:-
I have learnt English. (Learnt is part of the verb phrase 'have learnt')
For example:-
Her hair was well brushed.
For example:-
As an adjective: He had a broken arm. (Broken is used here as an adjective.)