Non-count nouns do not have a plural form; however, some nouns can be used in both the count and non-count sense:

Third-person singular "-s"

Singular and non-count nouns (in the third person) require the "-s" form of the verb in the present tense.

The girl loves painting.

My dog likes to eat meat.

Johnny lives next door to Jenny.

Milk contains nutrients.

Tommy has two hobbies.

Jerry is from Colorado.

Singular count nouns require an article (the, a, an) unless

they are "proper" nouns

Mr. Jones went to Arizona.

they are preceded by a possessive

My mother loves my father.

they are preceded by this, that, each, every, either, neither, or one.

Each man contributed one dollar.

(Wrong: Apple is on table. [Articles are required.])

The/An apple is on the table.

Plural nouns and singular non-count nouns do not require an article in the "generic" sense:

Water is important for plants.

However, they require articles (the, some) in most other cases.

Please put some wine in the glasses.