On the Home tab at the top of the window, in the Font group, select the font size from the drop down list or click Grow/ Shrink font in font group.
When you move your mouse over the font size, you can see a preview of the applied font.
Select desired font size from the drop down font list in font group; and then you will see that the text appears in the selected font size.

2
Click on the font size and select 14 from the dropdown list  
To increase the font size - Click the grow font in font group.
3
Click the grow font in font group