In English we have 's' at the back of the noun to identify it's plural or singular, however it's not apply to Chinese, with the noun itself, we can't tell. So we have to add the quantifier to show it's plural when it come to many.
For quantifier, it should be something like 两个,三间，四条，五把 and etc, measure-words would be the 个, 间, 条, 把 and etc.
In English, we just use one car, but in Chinese, we need to add the measure-words : 一辆汽车, different object will have different measure-words.
Certain measure-words do define the quantity like 一双，(a pair of) 一打(a dozen), 一排(a row of) but not all of them.
So what I mean is with the word cars, we can tell it's multiple cars. However we do not have something like 汽车s