Do it like this:

=IFERROR(VLOOKUP(walmart&1,$A$1:$C$4,3,FALSE),"")&IFERROR(" / "&VLOOKUP(walmart&2,$A$1:$C$4,3,FALSE),"")&IFERROR(" / "&VLOOKUP(walmart&3,$A$1:$C$4,3,FALSE),"")

You can extend it by highlighting the red part in the Formula bar, then CTRL-C, then move the cursor to the end of the formula and CTRL-V as many times as you need - you will have to manually change the 3 (shown in blue) to 4, 5, 6 etc. If you had the company names in another cell (e.g. E2), then you could replace that in the formula with a reference to the cell, like E2&1 rather than walmart&1, to make it more general.

Then copy the formula down.

Hope this helps.

Pete