With this usage, in these examples, we would normally require a/an before a singular countable noun: Have you got a glass for the beer? Have you got a vase for the flowers? I don't have a suitcase ...

I have three exams on my birthday. These are known as “countable” nouns. But some nouns are “uncountable”. These are things that are a concept, or not easy to divide. In general ...

Other examples include: economics ... When you want to show a plural countable noun, you use a 's' e.g. a hat / 3 hats. Uncountable nouns have no plural and always use a singular verb.