^start of line
\s*any whitespace character, repeated any number of times
Positive Lookahead(?=\w(?:.{0,30}\w)?\s*$) \wany word character
Non-Capturing Group(?:.{0,30}\w)? ?repeats the group contents below at most once:
.{0,30}any character (except for line terminators), repeated between 0 and 30 times
\wany word character
\s*any whitespace character, repeated any number of times
$end of line
\w+any word character, repeated at least once
Non-Capturing Group(?:\s\w+)* *repeats the group contents below any number of times:
\sany whitespace character
\w+any word character, repeated at least once
\s*any whitespace character, repeated any number of times
$end of line
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