Logs for the firewall and related processes may all be found under Status > System Logs.
Logs messages generated by pfSense, the Operating System, and other applications which do not have their own logging tabs show on the first tab, System on the General sub-tab.
If something is not working properly, a message may be found here indicating an error condition or informational messages about system activity.
Logs for other subsystems are located on individual tabs at the top of the log view. Click on a tab to view one of the other logs, or click the Settings tab to make changes to the logging behavior.