Any is normally used with plural and uncountable nouns in questions, negative and conditional sentences: Do we have any beer? ~ Yes, we do. It's in the fridge. Do we have any glasses? ~ Yes, we do.

Is any a plural or singular?

With singular uncountable nouns (also called mass nouns), any is singular. This is because uncountable nouns (like water, furniture, jewelry) are thought of in terms of quantity rather than a countable number.

Should I add s after any?

If you use any or some with countable nouns, the nouns should be plural, i.e. you should add an 's'. If the noun following any or some is uncountable, don't add an 's'.