F*** is an English word that, as a transitive verb, means "to have sexual intercourse with". It also has various metaphorical meanings:
The verb "to be f****d" can mean "to be cheated" (e.g. "I got f****d by a scam artist").
As a noun "a f***" or "a f****r" may describe a contemptible person.
"A f***" may mean a sexual partner.
"F***" as a verb can be used as an interjection, and its participle f***ing is sometimes used as a strong emphatic. The verb to f*** may be used transitively or intransitively, and it appears in compounds, including f*** off, f*** up, and f*** with.
In less explicit usages (but still regarded as vulgar), f*** can mean to mess around, or to deal with unfairly or harshly.
In a phrase such as "don't give a f***", the word is the equivalent of "damn", in the sense of something having little value. In "what the f***", it serves merely as an intensive.