StringPadRight

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

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

Examples

Pad with spaces:

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

Pad with custom character:

StringPadRight["test", 10, "-"]
(* "test------" *)

Please visit the official Wolfram Language Reference for more details.