With Routines, Google Assistant makes it easier to do the things you do every day. In the morning you can just say “Ok Google, good morning” and your Assistant will do things like tell you the weather, read you your calendar events, play your favorite podcast and much more. You can personalize your Routines to turn off the lights and change the thermostat when you go to bed or send a text to your partner when you’re getting in your car to drive home.
I lead the design of this project, thinking both about how users set up their Routines as well as how Routines run on phones, speakers, and smart displays.
Source. Also check out “Get this party started” video
Setting up an Assistant Routine on the phone is easy, just tap the actions you want for each routine or add your own custom actions.