This app is intended for use in a situation where you want or need to keep track of time but want to avoid looking at your watch. It can be used with an iPhone alone, but is designed to work best with a iPhone linked to an Apple Watch.
Say you are running a small meeting expected to last 50 minutes. You know that discussion may distract you and would like to know when you are 15, 30 and 42 minutes into the meeting. You can program the app to cause your Apple Watch to tap you on the wrist once at 15 minutes, twice at 30 minutes and three times at 42 minutes. Many other patterns are available.