From there, you can see times in white, yellow or red, indicating spaces where everyone is available (or not). Then, you can tap the time picker and drag it around until it turns green, giving you a slot that works for everyone. From there, you can fill in the rest of the information and save the event, which will automatically notify the other parties.
Many of Outlook's calendar features come directly from Sunrise, so at least Microsoft is using the IP it paid for. Redmond integrated Sunrise's "events" and "interesting calendars" feature last month, and added the time and date picker shortly afterwards. The scheduling assistant from Outlook desktop is icing on the cake, but whether it convinces diehard Sunrise fans to switch remains to be seen. The new feature is only on iOS, but is coming to Android and Windows 10 Mobile "shortly."