Regex option from Text processing

[alkido]

Want to check from a table of two columns: A - Email and B being X
I need to confirm if col A (email) is an actual email by using a Regex so I set top text processing text being my variable
e.g {-Variable.RegexedEmail-}
I select Regex dropdown, set my Regex script in Regex field
and then below I need to set back to the same variable (like a replace).
But confused and do not see any docs on confusing term: "What to get: To variables", which I assume it will put it back to a variable that I set below in the table, but the wording sounds like its some sort of PUT only?
No: 1 RegexedEmail

but what is the No. column mean?

Is the match No: field, how many matches?

I want to make sure if no email is found based on the regex, to keep the variable empty that gets put back into a new table column, as empty. Reason for this, is instead of emails, I see many script files (not emails) that I need to remove but keep rows intact.

Found this regex to use, so using this for ref:

[a-z0-9]+([-+._][a-z0-9]+){0,2}@.*?(\.(a(?:[cdefgilmnoqrstuwxz]|ero|(?:rp|si)a)|b(?:[abdefghijmnorstvwyz]iz)|c(?:[acdfghiklmnoruvxyz]|at|o(?:m|op))|d[ejkmoz]|e(?:[ceghrstu]|du)|f[ijkmor]|g(?:[abdefghilmnpqrstuwy]|ov)|h[kmnrtu]|i(?:[delmnoqrst]|n(?:fo|t))|j(?:[emop]|obs)|k[eghimnprwyz]|l[abcikrstuvy]|m(?:[acdeghklmnopqrstuvwxyz]|il|obi|useum)|n(?:[acefgilopruz]|ame|et)|o(?:m|rg)|p(?:[aefghklmnrstwy]|ro)|qa|r[eosuw]|s[abcdeghijklmnortuvyz]|t(?:[cdfghjklmnoprtvwz]|(?:rav)?el)|u[agkmsyz]|v[aceginu]|w[fs]|y[etu]|z[amw])\b){1,2}

Appreciate any help understanding the options with Text block for Regex and how to use.

Thanks