Need help in formula

I'm not sure I understand your exact inquiry.  I looked at your spreadsheet on the received Items sheet.  If you wanted to check to see if the Received Item in Column B is on the Stock Items Spreadsheet and there is a value > 0 in the stock items column you could use this formula:

=IFERROR(VLOOKUP($B4,'Stock Items'!$B$2:$N$6,13,FALSE),0)>0

and apply it to this range in order to get the entire row to change colors (In this case Purple):

=$A$4:$N$56

If you can clarify your inquiry with more specifics it will be easier for someone in the community to address your issue.  Please see attached for an example of how to accomplish the above.  If you are trying to use conditional formatting based on conditions present in another workbook this is not possible.