If it is just based on finding data that meets a condition, use the vlookup function; if you want to find the number of conditions to meet more than one, use the array formula, similar to: = sum(--(worksheet 2!A1:A10="Computer")*(worksheet 2!B1:B10="Extranet")*(worksheet 2!C1:C10=""))
That's it.
Note that the array formula is written to press Ctrl + Shift + Enter, not directly press Enter.