SQL query which includes COUNT(*) in it's SELECT `clause` confuses me

I’m a newbie in SQL, trying to find my way through.

I have the following diagram:

and I’m being requested to

"Produce a list of number of items from each product which was ordered
in June 2004. Assume there’s a function MONTH() and YEAR()"

The given solution is:

SELECT cat_num, COUNT(*)
FROM ord_rec AS O, include AS I
WHERE O.ord_num = I.ord_num AND
MONTH(O.ord_date) = 6 AND
YEAR(O.ord_date) = 2004
GROUP BY cat_num;

What I’m confused about is the COUNT(*). (specifically the asterisk within).

Does it COUNT all rows that are returned from the given query? So the asterisk refers to all of the returned ROWS? or am I far off?

Is it any different than having:

SELECT cat_num, COUNT(cat_num) 

Thanks!

>Solution :

The COUNT(*) function returns the number of rows in a dataset using the SELECT statement. The function counts rows with NULL, duplicate, and non-NULL values.

The COUNT(cat_num) function returns the number of rows that do not contain NULL values.

Consider an example:

For this data,using query:

SELECT 
  COUNT(*),
  COUNT(t.`Block`),
  COUNT(t.`Range`) 
FROM
  `test_table` t 

You’ll obtain results :

I hope that clears your confusion.