According to Wikipedia:
Speed dial is a function available on many telephone systems allowing the user to place a call by pressing a reduced number of keys. This function is particularly useful for phone users who dial certain numbers on a regular basis.
The Speed Dial extension of the Fast Dialer app, for Sony’s SmartWatch does exactly that. The Fast Dialer app is – of course – required to be installed on the host device (i.e. phone), and through it the speed dial numbers are set.
Calls are made by long tapping one of the displayed numbers.
Here’s a short video to see the app in action.
The app is free, get it today from Google Play: https://play.google.com/store/apps/details?id=eir.dialer3.extension.speeddial