Specific to the WoW API,
string.format() lets you specify which args go where by modifying the format specifier. By default, they are left-to-right in order. This would flip the order by specifying the second argument goes in the first slot and vice versa. Blizzard did this specifically to support localization.
Code:
FACTION_STANDING_INCREASED = "%2$d %1$s"
Note: The letters define the data type, changing these to be different than what the arguments are can cause type mismatch errors.