StringPadLeft

StringPadLeft["string", n] pads the string on the left with spaces to make it length n.

StringPadLeft["string", n, "padding"] pads with a custom padding string.

Examples

Pad with spaces:

StringPadLeft["hello", 10]
(* "     hello" *)

Pad with zeros:

StringPadLeft["42", 5, "0"]
(* "00042" *)

Please visit the official Wolfram Language Reference for more details.