"ttyl" is an acronym used in text messaging and it stands for "talk to you later". It is often used as a casual way to say goodbye or indicate that you will speak with someone again in the near future. In this context, it can be understood as a texter's equivalent to saying "bye for now".
Note: The provided meaning of the answer is for the latest New York Times crossword puzzle clue: "Cya". Explanations are generated by AI and may be inaccurate.