What happens to messages detected as spam by SpamAssassin?

In logs, I can see entries like:
PROCESSING:…: Filter SpamAssassin Filter(192.168.1.87:783):[MATCH(P)]: Spam: True ; 8.3 / 6.0
What happens to such messages? Is the SpamAssassin score added to the score of the other (Cyren, DNSBLs) checks? Averaged? I’m trying to understand how a message spam score is computed, and what SpamAssassin role is in that when enabled.
Thanks.