^start of line
\s*any whitespace character, repeated any number of times
\S+any non-whitespace character, repeated at least once
Non-Capturing Group(?:\s+\S+){4,} {4,}repeats the group contents below at least 4 times:
\s+any whitespace character, repeated at least once
\S+any non-whitespace 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