Hello and welcome.
-What version of OS X and Numbers?
-Are you using the Apple Mail and Address Book/Contacts apps?
You should be able to simply select and copy he column/row of email addresses in the Numbers spreadsheet, create an email in your mail app, and paste the email addresses into the To: field, and compose and send the email.
We may be able to help you make an email group for these email addresses as well, for future use.
C