In English, he and she are singular third person pronouns, which refer to men or women. And they are plural pronouns, referring to two or more people or things. Therefore, when it is necessary to refer to multiple men or women, it can be used as the plural form of he and she.
In addition, she can also be used as the plural form of she in informal occasions or oral communication, but it should be noted that this usage is not standardized and only applies to informal occasions or oral communication. In short, the plural forms of he and she can be them or her, and the specific use depends on the context and occasion.