The routines can be set up for one person, or more than one person, to use through Google Home devices. An example would be, "Hey Google, remind me to pick up milk when I'm at the store". Since your Google Home device stays at home, Google Assistant will then send you a reminder on your phone once you reached the location, assuming your location services are on.
For instance, users will be able to setup multiple actions based on a phrase such as "Hey Google, good morning".
So far, reports say routines appear to be working on both iOS and Android. It's live right now on a Home near you. You open the Alexa app on your phone, jump into settings and tap on the device you want to enable this new Follow-Up Mode for (it's off by default, as it should be). It's a set of multi-step actions triggered by one command - they're called Scenes in Apple HomeKit, Applets in IFTTT etc.
There are some limits, it seems, however. The Google Home range of speakers was toted to make your domestic life easier, and it wouldn't be very good at it if it lacked the ability to remind you of stuff.
Similarly, depending on how you phrase the request, the Assistant doesn't always recognize the difference between a general reminder and a location-based one. The national brands that have formally aligned with Google's voice-activated virtual assistant to accept spoken orders via the delivery marketplace Google Express include Costco, Guitar Center, Kohl's, L'Occitane, Payless, PetSmart, Road Runner Sports, Sur La Table, Ulta, Walgreens, Amazon's Whole Foods, Walmart's 4,700 stores, and Panera Bread. Saying "Ok Google, remind me to check tire pressure at the gas station", by example, wasn't understood in terms of the gas station being a location. I told it to remind me of something when I go to Target, and Home said it would remind me on my phone when I go to "a Target".