Regex making fields

I don’t understand following regex on https://mockaroo.com/help/regex/

\d{1,3},\d{2} {{currency}}

Are we referencing a predefined set called currency? If so, what is the syntax for making that set?

If I have a set of strings, Can I define a named set for that set of strings and reference that in regex (one random string from the set) ?

I’m kind of new to regular expressions.

Thank you everyone !! :slight_smile: