Translation:Mom does everything and dad does nothing.
I believe that originally כלום meant "something". In modern Hebrew, it is used in two ways:
- With a negation word like לא or אין before, as in this excercise; together they mean nothing (makes sense if כלום means "something").
- As a single-word answer to a question (e.g. מה אתה עושה? כלום). It means "nothing". This is a recent development of modern Hebrew, I believe. In writing of 50 years or more ago, you'll see מה אתה עושה? לא כלום. But because of this change, it's commonly thought that כלום means "nothing", and then the full-sentence usage with לא seems like a double negation, which is confusing.
Hope this helps...
They are used differently. שום always precedes a noun - שום איש, שום דבר (so אין שום does not work at all). On the other hand, כלום goes by itself to mean "nothing" - but it requires a negation word in the sentence, so יש כלום also doesn't work in Hebrew. Only אין כלום.