This appears to be a misspelling or truncation; if you meant 'have,' it's the auxiliary or main verb expressing possession, obligation, or completion.
If this is 'have': from Old English 'habban,' related to Old Saxon and Old High German words. The '-ve' contraction is very common in speech ('I've,' 'they've') and increasingly appears in informal writing.
The word 'have' is so overused we're actually letting it disappear in casual writing—texters write 'I got' instead, and 'hav' looks like autocorrect's cry for help, showing how language evolves even in its corruptions!
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