In English, just like in any other language, nouns can either be countable or uncountable.
When talking about uncountable nouns we can only use singular verbs. Also, the noun itself is never plural.
- Water here is cheap.
- The money is the only thing that matters to him.
Never use plural verbs when talking about uncountable nouns:
- Waters here are cheap.
Never use numbers when talking about uncountable nouns:
- I want two waters. (Water is uncountable so we can only say "I want two bottles of water")
Water is a good examples of an uncountable noun. But how do I know if a noun is countable or not? The best way is just to memorise the most tricky ones! Click here to see the list of uncountable nouns.