What does "canalla" mean?

I was speaking with my friend and he called his boss "canalla". Does anyone know what that means?

Canalla means scoundrel.

In Argentina the supporters of the soccer team Rosario Central are also called as Canallas.

The description would be:

That is despicable by his vile behavior, also can be said that is bad, evil.

And how would say here you have to bank it. :p

Yes, and riffraff can be another translation.

Riffraff?? I don't know the term, is an urban term??