I'm using this to build a personal database of who texts me so I can run interesting reports. eg most popular words, etc...
If
Any new SMS received
This Trigger fires every time you receive any new SMS on your Android device. Learn more
Then
Add row to spreadsheet
This action will add a single row to the bottom of the first worksheet of a spreadsheet you specify. Note: a new spreadsheet is created after 2000 rows. Learn more
Explore more great ways to automate Google Sheets and Android SMS