Split names into columns - Numbers

It can be done but it may not be perfect and it will require a third (temporary) column for the last name. The idea is to split it at the first space character. Anything to the left is first name. Anything to the right is last name. The space character itself gets dropped. But names don't always follow that convention. If someone has a multi-word first name or uses their first and middle as their "first" name, you'll have to manually fix it.

B2 =IFERROR(TEXTBEFORE(C2," "),C2)

D2 =IFERROR(TEXTAFTER(C2,B2&" "),"-")

Fill down with both to complete the columns

Select columns B-D

Copy

Paste Formula Results (this is in the Edit menu) to convert the formulas to values

Review the results and manually fix any that need fixing

Delete your old column C

With the more recent version(s) of Numbers, you only need to enter a formula in B and D and have them "spill" into all the rows below. For that the formulas will be

B2 =IFERROR(TEXTBEFORE(C," "),C)

D2 =IFERROR(TEXTAFTER(C,B&" "),"-")

No need to fill down. All the other steps are the same.