This section is available in the Adguard window (Settings - Log section) only if the extended interface is enabled.
This section allows you to monitor how Adguard filters ads. If the log is active, you see what browser requests have been processed and what filters have been applied to them.
The Log section will come in handy for advanced Adguard users creating their own filtration rules.
On the basic logging level, you only see requests that have been filtered and had rules (or anti-phishing and anti-malware filters) applied to them.
If detailed logging is enabled, the log contains all the requests processed by Adguard.