Time left to complete shows how much time you have left to complete the daily goal, and gain a streak for that day.
Epic app is set up in the UTC time zone. Depending on each country, the reset time of the application will be different, not necessarily every 00:00.
For example, in Vietnam with UTC +7 time zone, Epic is reset at 7 am every day. As shown in the image below, the current time is 15:53, and this user has 15 hours and 7 minutes to complete the daily goal before the application resets at 7 am the following day.