How many colums can you make on a excel?

That depends on the version you have. Up to and including Excel 2003, the standard amount of columns has been 256. They are labelled by letters. After Z you get AA, AB, AC etc. until you get to AZ. Then it is BA, BB, BC and so on. The 256th column is IV. In Excel 2007 the number of columns is 16,384 which means the last column is column XFD.

Excel 2007 can support up to 16,384 (A - XFD) columns, assuming your computer has enough memory to load everything.