Here are some possibilities:
* Typo for "Tak": This is the most likely scenario. "Tak" means "until" or "up to" in Hindi.
* Shorthand for "Thank You": In some online contexts, "tk" might be used as a shortened way of saying "Thank You".
* Specific Acronym: It could be an abbreviation used in a specific field or industry, like "TK" for "To Come" in project management.
Without more context, it's impossible to determine the exact meaning of "tk" in Hindi.