None is thought to be a shortened version of "no one". It is primarily used as a singular adverb and singular pronoun (with, of course, a few exceptions). For example: Pronoun 1. None (no one) dared to do it. 2. None (no part) of your business. Adverb 1. The trousers looked none (in no way) the better for having been washed. I hope this helps!

You might need to provide some context to get better answers. I would say 'none' is 'not any', or 'not one', and it is used as an amount. "How many? None." sg might mean solicitor general or Surgeon General, or a hundred other things (maybe Singapore, or single guy), but probably one of the first two. pl probably means plural, or (if used in a dictionary) it could mean 'place', as in a place name. If it is in a dictionary, there should be a list of abbreviations at the front that tell you what it means.