It usually means that is the amount of number and its spacing.
xxx-xxx-xxxx can be replaced by 123-456-7890. (xxx) xxx-xxxx would be a phone number such as (408) 123-4567
It usually means that is the amount of number and its spacing.
xxx-xxx-xxxx can be replaced by 123-456-7890. (xxx) xxx-xxxx would be a phone number such as (408) 123-4567