Need some help with lookup - I need to refer to a table and insert relevant info.

I have a work sheet containing various information including Store, Product Number, Quantity. I then have a separate sheet containing Product Number and Product Description. I would like to add the Product Description next to the Product Number in the first sheet.

The Product Number may appear several times and in a random order so I need to do some sort of lookup to say if Product Number = x then look up x on the second sheet and take the Description from the next column.

I hope this makes sense? Can anyone help?

Claire