How to split 'Full Name' into two columns for 'First' and 'Last' name??

The feature is not in Numbers but you can do it with formulas.

If the names are of the format lastname, firstname and are in column B then
column C formula for first name is =TRIM(RIGHT(B,LEN(B)-FIND(",",B)))
column D formula for last name is =LEFT(B,FIND(",",B)-1)

These simple formulas require that there be at least one character, a comma, and one other character (in that order). Anything less will result in an error. There can be a space after the comma; it will be removed.

If:

A1 = Fistname Lastname

For firstname:

(First Name) B1 =SUBSTITUTE($A1," " & $C1, "")

For the Last name:

(Last Name) C1 =RIGHT(A1,LEN(A1)-FIND("#",SUBSTITUTE(A1," ","#",LEN(A1)-LEN(SUBSTITUTE(A1," ","")))))

If

A1 = Lastname, Firstname

(Last Name) B1 =SUBSTITUTE($A1,", " & $C1, "")

(First Name) C1 =RIGHT($A1,LEN($A1)-FIND("#",SUBSTITUTE($A1," ","#",LEN($A1)-LEN(SUBSTITUTE($A1," ","")))))


Let me know if you need one that traps multiple commas or middle names.