The image below is the left half of a standard Ribbon in Excel. The Ribbon bar is broken up into sections. Clipboard, Font, Alignment, Number, Styles, Cells and Editing for the Home Ribbon.
The Number section is probably the significantly different section from other Home Ribbons. The default options are Currency (never use this – its pretty but distracting format wise), Percentage, Currency without signage (a comma and two decimal places) and the option to increase or decrease the number of decimal places visible.
Underneath the Ribbon bar on the left is the Name Box. Generally, that shows the name of any field or object that is in focus. In the above it shows L9 which means the focus cell is 12 columns over from the left and nine down from the top. Ranges of cells and individual cells can be given names. If focus is one of those, the name of that cell or range of Cells will appear in the Name Box. If focus is on a Pivot Table or Chart, the name of that object will appear in there. The name can be overwritten in that box.
To the right of the Name box are one or three symbols: the Function symbol (read as function of x in maths and is the symbol visible in the image above) is a quick access key to all of the formulae that Excel can use. If a formula is being written in a cell a cross and tick symbol appear. These are: delete the formula and accept the formula as written at present.
To the right of the function symbols is the Formula Bar. Any data or text added to a cell will appear in here. With more complex formulas and long text strings, it is often easier to edit from within the Formula Bar
The above is an image of the right hand side of the Ribbon Bar.
Styles are useful for some of the more esoteric functions in Excel as well as to change all formatting within a range of cells.
The Cells section does most things that right click does.
The Editing section allows some basic editing and Data Sorting as well as insertion and deletion of cells, columns and rows.