In the Font group in the Ribbon you can easily change the font type, the font size, the font color, the cell color (background color), and the font "texture" (bold, italics, underline).
There are a few more font formatting options that you can access by clicking on a specific cell or a group of selected cells and go to Format in the Menu and select Cells.... The Format Cells dialogue box that opens has a number of tabs. In the Font tab, there are additional font formatting options such as changing the underline type or striking through information in the cells. Text can also be changed to superscript or subscript. The Border tab and Fill tab also give you more formatting options than the Border and Fill links in the Font group in the Ribbon.
Alignment is both a group in the Ribbon and a tab in the Format Cells dialogue box.
Alignment allows you to align text (and numbers) in cells to the left, center, or to the right of the cell (horizontal alignment). It also allows you to align text towards the bottom, top, or center of the cell (vertical alignment). The different allignment options can be very useful for formatting data for readability. Also in Alignment is Wrap Text. Say you have a column header that is very long. You could increase the width of the column to see it in its entirety (see above) OR you could wrap the text so that it fit in the width of the column by making the row larger.
Here we have 3 headers, but only the final one can be read completely.
If we highlight the cells and select Wrap Text...
You can alter the column width so that words are not cut off. You can also set the horizontal and vertical alignments to your preference. In the Alignment group you can also change the orientation of the writing by clicking text orientation button. The dropdown arrow will give you orientation options. You can also change the indentation of the text by clicking on the indentation buttons just below the orientation button. Also, notice that the text was vertically centered in the following example. Selected Alignment items are highlighted with a darker grey.
Finally Merge & Center will allow you to merge selected cells and center the context in the newly created larger cell.
Number is both a group in the Ribbon and a tab in the Format Cells dialogue box.
Number allows you to format cells to different data types (general, date, time, number). By clicking on the arrow next to the Number Format bar (with default option "General") you can find many number formatting options, as well as Custom, which will take you to the Format Cells dialogue box.
In Number you can also adjust the number of decimal points, add monetary signs, change to a percent (which multiplies the information in a cell by 100 and adds %), or add commas (changing 1000 to 1,000).
You can change the monetary symbol by clicking the arrow next to it to open a menu for a few options and the option to open the Format Cells dialogue box for even more options.