It helps you save time and avoid mistakes when you are typing a series of information.
Type the first item in the series — January, for example.
Drag the fill handle across the cells that you want to fill.
To change the way that the cells are filled, click Auto Fill Options.
Tip: To repeat the word January in the cells, click Auto Fill Options > Copy Cells.
To have Excel automatically complete other kinds of lists, such as days of the week, start with the name of a day instead of the name of a month.
To create your own lists, click Excel > Preferences, and then under Formulas and Lists, click Custom Lists.