The sparkle button beside Add task lets you type something like "gym at 7pm tomorrow" and turns it into a real task with the right title, due date and time filled in automatically.
Only the text you type in that box is sent anywhere — nothing else about your account goes with it, and it only runs when you press that button.
This is a paid feature, with one free 24-hour pass per account so you can try it before deciding — see "Plans and billing".