COUNTIF checks a range of columns for a specified value, it then outputs the total number of columns with the specified value.
This can be useful if one is attempting to tabulate sums where the columns aren’t numbers but text. For example, if you have created a todo list and assigned certain individuals specific todo items, you can get a count of tasks assigned to a specific individual by using COUNTIF like so:
The above tells Google Sheets to count up the number of times the text “Dave” appears in column D between rows 10 and 100. If you had assigned “Dave” nine tasks then the result would be 9.