Relative Pronouns:

Who, Whom, Whose, Which, Where, When, Why.
Who: For humans as subject. Meaning in Indonesian is "Yang"
Whom: For humans as object. Meaning in Indonesian is "Yang"
Which: For non-humans as subject or object. Meaning in Indonesian is "Yang"
Whose: For possesion. Meaning in Indonesian is "Yang .... nya"

Explanations for Who, Whom, Which, and Whose;

Who
That is the lady who asked me the way to the station yesterday. (Itu adalah wanita yang bertanya kepadaku jalan ke arah stasiun kemarin). Here, Who=Yang is for human (the lady), and is followed by asked=bertanya. It means Who=Yang is a subject(who-the lady-asked. the lady=suject, asked=predicate.

Whom
I know the man whom you met at the hall lastnight. (Saya kenal laki-laki yang kamu jumpai di aula tadi malam). Here, whom=yang is for human(the man), and is followed by you met. from you met, the subject is you. so, whom must be object.

Which
That is the computer which father bought yesterday. (Itu adalah komputer yang di beli ayah kemarin).Yang=which is for non human(the computer).

Whose
The boy whose bike was stolen last week is still very sad now. (Anak laki-laki yang sepedanya di curi minggu lalu masih sangat sedih sekarang). here, whose= yang...nya, in this sentence whose bike=yang sepeda nya. it shows possession.

Where, When, and Why:
Where is a relative pronoun used to show place.
This city is where I was born. Here, where is used as a reference for (Sebagai acuan untuk) this city.
When is a relative pronoun used to show time.
I do not renenber the day when I visited her place. Here, when is used as a reference for the day.
Why is a relative pronoun used to explain a reason.