Is "people" a countable or uncountable noun? "People in Japan also eat sushi."
People is a countable noun.
For example, you can say:
"I can see five people on that bridge"
But you cannot say:
"There are five weathers over that bridge"
This is because you can have plural people but you can't have plural weathers - so countable nouns can be plural and uncountable nouns cannot be plural.
Hope this helped!