^start of line
Athe literal A (6510 / 1018 / 4116) (case sensitive)
Non-Capturing Group(?:(?![A-Z]{2}).)*? *?repeats the group contents below any number of times:
Negative Lookahead(?![A-Z]{2}) {2}matches exactly 2 characters from the set below:
A-Zone character from A (6510) to Z (9010) (case sensitive)
.any character (except for line terminators)
\Kresets the starting point of the reported match. Any previously consumed characters are no longer included in the final match
\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