- Singular: One of [whatever the noun or pronoun represents].
- Dual: Two of them.
- Plural: More than two of them.
Many non-Indo-European languages still have this singular/dual/plural paradigm. Nouns have three different forms. But I think it's extinct in the modern Indo-European languages. We all have just singular/plural, so for us plural means "more than one." Our nouns have only two forms: Dog/dogs, man/men.
Chinese has no inflections at all, so nouns do not indicate number; there is no singular and plural. When you say dog, person, day, idea, there is no indication as to how many of them you mean. Many times it doesn't matter: "Coyotes eat rabbits," the number is irrelevant. Other times it's obvious from context: "Son ride motorcycle," everyone knows you have only one son and everyone knows you can only ride one motorcycle at a time. But when it's important you just say the number: "All coyote, several rabbit, three son, one motorcycle."