It's possible that:
* It's a misspelling: Perhaps you meant a similar word like "what," "that," or "eat."
* It's a slang term: It could be a regional slang word or an internet slang term. Without more context, it's impossible to know.
* It's a technical term: It could be an abbreviation or acronym used in a specific field of study or profession.
Please provide more context about where you encountered the word "ehat" so I can help you figure out what it means.