Translation:You stand next to this curtain, and you stand next to that one, okay?
Perhaps a group of schoolchildren are putting on a play. There are several different curtains on the stage as a backdrop.
The teacher talks to two children who are supposed to stand at a certain location on the stage -- one child should stand by a curtain at one end of the stage and the other child should stand by a curtain at the other end of the stage.
So the teacher says to the first child, "You stand next to this curtain," and then turning to the other child and pointing to the curtain at the other end of the stage, "and you stand next to that one," and then to confirm that they heard and understood him, adds, "okay?".
Great scenario! I thought of the theater, too, with this sentence. My question is.....could this not also be translated "at this curtain, at that curtain" just as you explained it in your second paragraph. I was marked wrong, but it seems a closer translation of -hoz/hez than "next to".
“-hoz, -hez, -hóz” are áll different forms of the same suffix that means movement towards something/someone. In English we use the word ‘to’ to express movement towards a noun. Which vowel you use in the suffix is based on vowel harmony rules. “-nál, -nel” expresses the idea of something/someone beside or next to something/someone but no movement is being expressed by that suffix. It carries the idea of a stationary position. Again, which vowel you use in the suffix is determined by vowel harmony rules. I’m an English speaker, my answer is based on my understanding in my learning through several resources.
Függönyhöz = You (go and) stand by that curtain Függönynel = You are (already) standing by that curtain.
Hez implies motion towards something even if the verb suggests otherwise. The (go and) that I put in paretheses is understood even if not expressed in Hungarian. The postposition makes that motion clear enough not to need the verb "to go". If I were translating from Hungarian, I would definitely add it to the English as otherwise the sentence is potentially misleading in the absence of context.