She liked chocolate. She liked the chocolate. The same applies to all Russian nouns. Children for whom Chinese is the mother tongue frequently have difficulty with articles in English because Chinese does not usually have them. Cats , horses , chairs , bikes are regular plurals.
Some English nouns have irregular plurals.
Some English nouns have slightly different spellings in the plural. This shows that they have learned the general rule about how to make a plural in English. They will learn irregular forms later as they build up experience. Not all languages have singular and plural forms for nouns. In Maori, and in spoken French, a plural is indicated by a change in the definite article rather than in the noun itself.