"The boy plays with his toys."
Translation:Drengen leger med sit legetøj.
This rule may work, but it is not correct to say that legetøj means *play-clothes.
"Tøj" has a lot more meanings, similar to "stuff", "tool", "thing", "material", and even "junk". And then it makes more sense: toys are "play things".
If you really want to go into the meaning of words, use the Ordbog over det danske sprog, https://ordnet.dk/ods/ordbog?query=tøj
Apparently both "toy" and "toys" translate to "legetøj". It appears to be always grammatically singular, like English "clothing" or "rice". I made this mistake too, writing "sine legetøj" instead of the correct "sit legetøj". So the answer to your question is no, it can translate to either the singular or the plural in English.
Jeg håber, du ser denne besked her. :)
"The boy plays with his toys" og det rigtige svar var ''Drengen leger med sit legetøj.''
Men det accepterede ikke ''Drengen spiller med sit legetøj.''
Synes du det er forkert at bruge ''spiller'' i stedet for ''leger'' ?
Yes, it would be wrong to use "spiller". We use "spiller" in the sense of "playing" with physical games, computer/video games and with instruments. "At lege" is used for toys, for the make-believe that we are doing as children, playing on a playground etc.
"his own toys" would be "hans eget legetøj"
But since "legetøj" is an uncountable, like "tøj" we have to use a quantifier (don't know if that's the right word) if we want to be specific about the numbers of it. In this case we use "stykke" (piece).
"his own toy" would be "hans eget stykke legetøj"
sin, sit and sine works like adjectives work in the sense that "sin" is singular, used for common gender words. "Sit" is also singular, but used with neuter gender words and "sine" is plural and is used as such.