Time left to complete shows how much time you have left to complete the daily goal, and gain a streak for that day. Every 24 hours, the system will reset.
The eJOY 2 system operates on UTC timezone. Therefore, a day isn't counted from 00:00 to 23:59, but varies depending on each region's timezone.
For instance, in Vietnam, which is in the UTC+7 timezone, EJOY 2 resets at 7:00 AM daily. This means you have from 7:00 AM today until 6:59 AM the following day to complete your streak.