The complaints column is the number of times a constituent clicked the “Spam” button in their email client. Typically this is high after a mailing to a new purchased list, or if they are using spammy subject lines.
As for spam traps, this is an indicator of the health of your email address lists. The more spam traps your messages hit, the more likely your messages will be perceived as spam by email service providers in the future. Taking a step back, a spam trap is an old email account that once was active and used for regular email. After a time, the owner of that email account abandoned it and ceased using it. After some time, it's common practice for the email provider to seize that old email account and turn it into a trap to better recognize spammers. Since spammers care little about where their emails go, they tend not to worry about cleaning up their email lists and removing inactive accounts. Thus, when one of your newsletters goes into that spam trap account, the email provider recognizes it as potential spam, and your sender reputation for future mailings is tarnished, making it more likely that your newsletters will head straight to a spam folder rather than the regular inbox.