Translation:What are those small colourful pictures on your sweaters?
It can apply to a number of types of clothing that can (or must) be pulled over the head to put on, for example, a shirt made of a stretchy material and that has no opening in front, or a dress, or a sleeveless dress that is meant to have a shirt underneath (often called a "jumper").
Yes, if only one person were addressed, it would be 'pulóvereden' ('on [sing.] your jumper').
If [sing.] you (=te) own more jumpers then it is 'pulóvereiden'.
The '(ti) pulóveretek' is '[plural] your jumper'. However, it is ambiguous if there is only one jumper that several of you own/wear (e.g. a mother and her daughter wear the same, at different times) or there are more that each of 'you' wear/own.
Also, there is '(ti) pulóvereitek' = '[plural] your jumpers'. Here we are certain that there are more than one jumpers that you own.
To nit-pick here - "colo(u)red" implies that color has been added to something that didn't have much color to start with. "Colorful" can also mean color has been added, but also refers to something that naturally has a lot of color. In this course I've seen the word színes applied to madár, and presumably, nobody used any paint to make it that way. :)
Nope. "That is red colored" - ie the colour of that is red. No painting required ie "coloured" is the attributed of HAVING colour as opposed to being white/grey/black. This is what szines means. "Colourful" implies brightly coloured or multi-coloured. Closer translation would be maybe viragos.