My mother doesn't entertain much any longer, because of her health.
Entertain?? What does this 'entertein' mean? 'Think about' or something? And what is this 'much' grammatically? The direct object of 'entertain? Or an adverb to modify the verb 'entertain' in front?
'doesn't entertain much' = doesn't provide much entertainment

Something she might do as hostess, --entertaining guests in her home, for instance, like providing music, games, setting a nice table, and encouraging amusing dinner conversations, etc.
Site Hint: Check out our list of pronunciation videos.
Ah! So it's an intransitive verb, and 'much' in the original sentence is adverbial!

I don't know why I didn't understand it!

Thanks, davkett---as always!
Or you might take 'much' as 'often': 'she doesn't invite people round very often'.