In most cases, the word is essentially meaningless. In others (when used as a verb) it's use is entirely unclear without context. Not really a versatile or useful word, so much as a word that's become so overused as an adjective, verb, or interjection that it's lost all meaning and can be inserted in any place in any sentence without significantly changing the meaning.
These aren't my words but they say it better than I can. "It is a magical word which, just by its sound can describe pain, pleasure, love, and hate. In language, "fuck" falls into many grammatical categories. It can be used as a verb both transitive (John fucked Mary) and intransitive (Mary was fucked by John). It can be an action verb (John really gives a fuck), a passive verb (Mary really doesn't give a fuck), and adverb (Mary is fucking interested in John), or as a noun (Mary is a terrific fuck). It can also be used as an interjection (Fuck! I'm late for my date with Mary). It can even be used as a conjunction (Mary is easy, fuck she's also stupid). As you can see there are very few words with the overall versatility of the word fuck."
Horror: Oh fuck!
Bad luck: Fuck, fuck, fuck...
Can't be fucked means can't be bothered
I'm surprised other countries don't know it