Eg.
1) She is the woman who loves me
Pronoun = who
Relative clause = who loves me
Main Action = Loves
Subject = Woman (= who)
Object = me
2) She is the woman whom I love
Pronoun = Whom*
Relative Clause = Whom I love
Main Action = Love
Subject = I
Object = She (= whom)
* Objects can be omited without changing the sense of the sentence.
3) He is the guy who sold the car.
Pronoun = who
Relative clause = Who sold the car
Main Action = Sold
Subject = he ( =who)
Object = the car
4) He is the guy whom we saw in the car
Pronoun = Whom
Relative clause = we saw in the car
Main Action = Saw
Subject = we
Object = he (= whom)
Who an whom refer to a person.
Person
Though who is the subject of the clause, while whom is the object.
The subject is the one who executes the main action.
The object is the element which suffers the main action.
See more examples
1) Mary is the lady who will talk to you in a minute.
Pronoun = who
Relative clause = who will talk to you
Main Action = talk
Subject = Mary ( = who )
Object = you.
2) Mary is the one to whom I will talk.
Pronoun= Whom
Relative clause = to whom I will talk
Main action = talk
Subject = I ( I will talk)
Object = Mary (whom)
