There are two tabbed pages in the Single Session History window:
The "History" page presents waits history for a single session. This information can be useful for monitoring and troubleshooting long-running queries or sessions running batch of queries. This window is very similar to Activity Explorer; the only difference is the single session scope. Please see help section for Activity Explorer for a detailed description of this window.
If the session is still alive, the current state can be explored in the "Current" page. This page shows the 10 last waits of this session using v$session_wait_history view. The page also shows cumulative waits per wait class (based on v$session_wait_class view) and session statistics (based on v$sesstat view).