The usual way to create this kind of summary would be to use a pivot table, but you can easily create a COUNTIF with multiple criteria by using its counterpart function: COUNTIFS.
To count all instances where column E shows 'A' and column M is greater than 0, you can use this formula:
The COUNTIFS function is covered in Expert Skills Session 3: Advanced Functions (lesson 3-6).
Pivot Tables are covered in Expert Skills Session 8: Pivot Tables.
I hope this is the solution you were looking for, but please feel free to reply if you need any more help with this.
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