1. Excel Auto-detection

Excel is very clever in detecting patterns in a set of values. If you are in the middle of inputing your data, pay attention to the suggestions of Excel which will be shown in small window with grey text. Once you see this, press 'Enter' and viola your column will be filled automatically. See screen recording below as an example.

2. Using Ribbon Menu

Another way to access the 'Flash Fill' is by accessing it from the ribbon. Once you have the first data entered, go to Data > Flash Fill. Excel will fill the column depending on the first inputted value. See recording below for example.