^start of line
Non-Capturing Group(?:.*\P{L})? ?repeats the group contents below at most once:
.*any character (except for line terminators), repeated any number of times
\P{L}characters not matched by \p{L}
\Kresets the starting point of the reported match. Any previously consumed characters are no longer included in the final match
\p{L}+any Unicode letter, repeated at least once
-the literal - (4510 / 558 / 2D16)
\d+a digit, repeated at least once
g modifier: global. Finds all matches instead of stopping after the first
m modifier: multiline. Causes ^ and $ to match the start and end of each line, not only the start and end of the string