One person, place or thing is a singular noun. Having more than one things, or having multiple people or places, that's referring to plural nouns.
For example,
- One school = singular
- Two schools = plural
We simply add s to the end of the noun for a lot of cases to make it a plural form. Though sometimes you'll have something like this
- One cross = singular
- Two crosses = plural
Note how we add on 'es' instead of simply 's'. This is so won't have a string of 's' letters at the end, and it adds on another syllable as well.
Some nouns are the same whether singular or plural. Such examples are
So you could say something like "I caught one fish yesterday" or "The biologist estimates there are about 200 fish in the lake".