why doesn't לה אין ילדים work?
What does לה mean??
Literally, ‹to her›. The sentence here says ‘There are no children to her.’ (or word for word, ‘there-are-no to-her children’), which is how you say ‹She has no children.› in Hebrew.
'ên leh yeledîm.
ein lah yeladím
Why can't it be בנים instead of ילדים?
Because בנים is sons and ילדים children.