What function do i use to retrieve the count from multi category?

Try a COUNTIFS.

=COUNTIFS([Column1]:[Column1], @cell = "Internal", [Column2]:[Column2], @cell = "PC")

You need to use a COUNTIFS (with the "S" on the end) to have multiple range/criteria sets, and it looks like you have your ranges set up to look at columns on the same sheet. If you are wanting to reference another sheet, then you would need to create your ranges with cross sheet references.

Start typing

=COUNTIFS(

Click on the blue text in the formula helper box that says "Reference Another Sheet".

Select the appropriate sheet you want to reference from the list on the left.

Click the column header that contains the data you want to evaluate for that particular range.

Optional: Rename the range.

Click on the "Insert Reference" button in the bottom right corner.

It should then take you back to the sheet you are working in and you will now have

=COUTNIFS({Range Name}

Enter a comma then enter your criteria, comma, set up second range, comma, second criteria, closed parenthesis.