pl. is the abbreviation of plural plural

Take the word content as an example. In the Oxford Advanced Learner's Dictionary, one of the meanings of the word content reads contents [pl.], that is to say, s is added after the word content. The expression of contents [pl.] tells us that contents is the plural form of the word content.

For collective nouns like people, if the singular and plural forms are the same, just use parentheses to indicate [pl.] directly after the word people to indicate that the plural form of people is also written as people.

Note:

The word content has a plural form when it expresses the following meaning. The plural form is the things contained by contents

; specific content [pl.]

Show me the contents of your suitcase.

Show me the contents of your suitcase.

The contents of the letter are secret.

The specific contents of this letter are not public.

Directory (of books, periodicals, etc.) [pl.]