Your formula calculates the sum of all the values in the given range and then divides that total by the number of cells that contain numbers, other than zero.
The division by zero error means that the SUMPRODUCT() function is returning zero.
The most likely reason is that all the cells in the range E2:E47 contain text, not proper numbers. The cell contents display as numbers, and many Excel functions will treat them as numbers by doing an intrinsic conversion, but SUMPRODUCT isn't doing that.
Try this function: =COUNT(E2:E47)
If it returns zero, then there are no 'real' numbers in the range.
If you get zero from the count function, try changing the cell contents to real numbers.
In cell F2 enter this: =VALUE(E2)
Drag the formula down to F47
Copy F2 to F47
Select E2 and Paste Special Paste values
Delete the formulas in column F
Hope this helps