SELECT agency_name, Count(*) AS complaint_type_count
FROM service_request_xs
GROUP BY agency_name
ORDER BY Count(*) DESC;
You have to tell the count() function what to count. You can insert an individual column, or * for all of it etc. But you have to count something.
This is a fiddle, showing how it works: https://www.db-fiddle.com/f/dbPnE4BXv8oRRkQY4WQs8v/1
SELECT agency_name,
COUNT(DISTINCT compliant_type) AS complaint_type_count
FROM service_request_xs
GROUP BY agency_name
ORDER BY COUNT(DISTINCT compliant_type) DESC;