Each cell contains some text and a background color. So I have some cells that are blue and some that are red. What function do I use to count the number of red cells?
Yes VBA is the way to go.
But, if you don't need to have a cell with formula that auto-counts/updates the number of cells with a particular colour, an alternative is simply to use the 'Find and Replace' function and format the cell to have the appropriate colour fill.
Hitting 'Find All' will give you the total number of cells found at the bottom left of the dialogue box.
This becomes especially useful if your search range is massive. The VBA script will be very slow but the 'Find and Replace' function will still be very quick.