In the modern versions of MS Excel (e.g, Office 365), the maximum numbers of columns and rows in each spreadsheet is 16.384 and 1.048.576, respectively.
To jump to the last column:
A letter or a combination of letters is used to name each column. The last one is XFD.
To see the last row of an Excel spreadsheet, you can use:
A number is assigned to each row. The largest one is 1.048.576.
In general, you will rarely need more than one hundred thousand rows and a few dozen of columns.