It meant "oll korrect".

Origin: In the 1830s, it was a trend in Boston and other parts of the U.S. to use humorous abbreviations. For example, people might abbreviate "no go" as KG (standing for "know go"). In this context, OK originated as an abbreviation for "oll korrect," a humorous misspelling of "all correct." The abbreviation gained widespread popularity during the 1840 U.S. presidential campaign of Martin Van Buren. Van Buren, whose nickname was "Old Kinderhook" (a reference to his hometown, Kinderhook, New York), used OK as a slogan. Supporters formed the "OK Club" to promote his candidacy. This association helped OK enter common usage. OK became widely recognized not just in the U.S. but internationally due to its simplicity and ease of pronunciation across languages