"We hope that she will come home."
Translation:Kami berharap dia pulang.
"That" in english can mean several things. As in:
That book (demonstrative) --> itu
The book that you read (relative pronoun) --> yang
I know that you are reading a book. (subordinating conjunction) -->agar,bahwa
"Yang" only has the meaning of a relative pronoun, while in the sentence above, you need the meaning of "subordinating conjunction", which in this case seems to be "agar" (see discussion above). I have also heard of "bahwa" as a subordinating conjunction, but I do not know what difference there is between "agar" and "bahwa".
One difference between "yang" and "that" (in the relative pronoun sense) is that "yang" can stand alone to a much larger extent than English "that" can, as seen in sentences like (from another Duolingo sentence):
Ada yang bergerak [...] there is (something) that moves [...], where "something" is not necessary in indonesian, but obligatory in English.
Yes, and there is one thing that you need be aware of: 'agar' and 'bahwa' have different meanings and usage.
When translating the current English sentence, I wouldn't use a conjunction word at all in the Indonesian sentence.
'agar' (= 'supaya') = so that. ==> conjunction word indicating 'hope' (cause and effect).
It's used to connect two clauses, like this :
"Kita belajar setiap hari agar/supaya tidak lupa."
"We study every day so that we don't forget."
"We study every day in the hope that we don't forget."
'bahwa' (and 'yang') cannot be used in the above sentence.
'bahwa' is used in the following sentence:
The English sentence there also uses the word 'that, and it's translated with 'bahwa'.
In that sentence discussion, there is also an example with the use of 'yang'.