The rules for the word order are not very in the English language are not very difficult to understand:
subject / adverb of frequency / verb / object (SVO) / time before place
A relative clause is a subclause which describes an object more in detail.
It is initiated by a relative pronoun.
The relative clause is initiated by "which" if the the object it refers to is an item or a thing.
I like coffee which is hot.
If the relative pronoun refers to person. who.
I like people who are nice.
The relative pronoun that can be used for people as well as for things.
I like coffee that is hot.
I like people that are nice.
The relative pronoun "whose" can be used in relation to context or ownership.
It can be used for people as well as for things.
The car whose door is broken.
The man whose wife is ill.
leaving out ot the relative pronoun
If the relative pronoun is used a indirect object you can leave it out.
The car (that) I was looking for.
The man (who) I worked for.