Possible Interpretations:
* Misspelling of "Yes": It could be a playful or informal way of saying "yes."
* Slang Term: It's possible that "yassus" is a slang word specific to a certain community or region.
* Foreign Language: "Yassus" might be a word from another language, perhaps a mispronunciation or a dialectal variation.
To understand the meaning, you need more context.
Please provide more information:
* Where did you hear or see the word "yassus"?
* What was the context of the conversation or writing?
* Who said or wrote it?
With more information, I can help you figure out the meaning of "yassus."