Nested if and Vlookup function problem - multiple worksheets

I was given a job for work that is too large to do manually, but I am not terribly good at using excel, so I was hoping you could help!

I have two workbooks, each with similar information in different formats. The first spreadsheet has a company listed one time with a column for data next to it. On the second spreadsheet the same company is listed multiple times, with data needs to be entered into the first. However, the tricky part is that we want the numbers entered into one cell, but not added, just listed. Is there a formula that will do this?