^start of line
yellow_ythe literal text yellow_y (case sensitive) \s+any whitespace character, repeated at least once
\Kresets the starting point of the reported match. Any previously consumed characters are no longer included in the final match
\S+any non-whitespace character, 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