•Regex settings use .NET Framework regular expressions to search for patterns.,
e.g., headerLinesRegex defines what a file's header looks like.
An online tester like regexplanet.com can help to understand them.
•Regex Named Groups settings are regular expressions that contain named groups,
e.g., seriesUnitColumnHeaderRegexGroups captures a series' unit from the column's header text.
Dot Net Perls (the second snippet of code, colored in blue) has a simple example that nicely illustrates capturing a regex named group's value.
A named group looks like: (?'name'subexpression), or (?<name>subexpression),
where name is the group's name (and cannot begin with a number or contain punctuation characters),
and subexpression is the pattern to capture.
If there is more than one named group, and/or more than one match is found, the agent joins the values using colons (:).