Nobody likes making spreadsheets, so Google is introducing Smart Fill for Google Sheets to help ease the pain. It basically checks previous columns for patterns, offering options to autofill the entirety of the next column based on what it thinks you'll want.
Smart Fill is best explained by the GIF above that Google provided. In this example, it sees that column C is simply "Hi *first name in column A*" once you fill in the same row. The same goes for column D, in which it autofills email addresses, and column E, when it simply pulls the ZIP codes from column B.
This functionality is rolling out now, and it will be on by default. Those on the Rapid Release schedule could get it starting today, but Scheduled Release domains will only start getting it starting November 5th.