Translation:The television that stands next to the new table is expensive.
The explanation I have heard is that relative clauses cannot be focused in Hungarian.
So, in this exercise, "Az a televízío" is focused by the implied verb "van". There is no room to put the relative clause after "That television" (as we would in English) because then the relative clause would be focused by "van", which is not allowed; therefore it is moved safely to the end of the sentence.
Actually, they don't have to. You can express the same idea by saying: "Az a televízió, amely az új asztal mellett áll, drága." However, I the Hungarian - especially the written one - also uses the participial structures quite excessively, so the very same idea can be expressed more elegantly with: "Az új asztal melett álló televízió drága."
This is an incorrect translation.
The english says: "the tv next to the table is expensive." The Hungarian says: "the expensive tv is the one next to the table."
These are not the same sentence.
The english is describing the tv. The Hungarian is deacribing the tv in relation to other tvs.