To count the number of cells in a column that do not contain a certain text string, follow these steps:

1. Select the cell where you want to display the result of the count.
2. Type the formula
   Formula:

   =COUNTIF(range,"<"&text) 

   into the formula bar, where "range" is the range of cells you want to count and "text" is the text string you want to exclude.
3. Press Enter to calculate the result.

For example, if you want to count the number of cells in column A that do not contain the text string "apple", you would use the formula .

This formula works by using the "<" operator to exclude cells that contain the specified text string, and concatenating the text string with the "&" symbol to include cells that do not contain an exact match of the text string.