Maybe the following will help.
You have two tables, one in Excel and one in JMP. Make a JMP version of your Excel table. Then, via the toolbar go to Tables --> Join. There you can match your columns in the "Matching Specification" panel. At least for me, table joining (and splitting) operations are typically error prone before I get them right, so I strongly advise to tick "Keep dialog open" when testing whether this method can work for you.
![Ressel_2-1660218288600.png Ressel_2-1660218288600.png](https://community.jmp.com/t5/image/serverpage/image-id/44738iCCC6950E3E9513E7/image-dimensions/461x496?v=v2)