An enemy; the Vietcong; short for Victor Charlie.
"The old truck was affectionately nicknamed Charlie, which is an alternative form of that name."
Alternative form of Charlie
In plain English: Charlie is not an official word with a single common meaning, so it usually just refers to someone named Charlie unless used as slang for something specific like a mistake or a person's name depending on the context.
"Charlie is my brother's nickname because he was born on his parents' anniversary to celebrate their love story."
A unisex given name
"Charlie is a popular unisex given name that has been used by both boys and girls throughout history."
A diminutive of the male given name Charles; also used as a formal given name.
"Charlie is often considered a friendly nickname for Charles, though some people choose it as their own formal first name."