them
"Them" is a very common English pronoun with a couple of closely related uses. It refers to people or things that have already been mentioned, and it also has a modern use as a singular pronoun for a person whose gender is not specified or who identifies as non-binary.
This is the most common use. When you have already mentioned a group of people or things, you use 'them' instead of repeating the full name. Think of it as the object form of 'they' — just like 'he' becomes 'him', 'they' becomes 'them' when it is the object of the sentence.
everyday language · Modern, widely used
Some people identify as non-binary, meaning they do not identify as strictly male or female. These individuals may use 'they/them' as their personal pronouns. So when you talk about that specific person, you use 'them' the same way you would use 'him' or 'her'.
everyday language, social contexts · Modern, increasingly common