Choosing Thread > Step Out in a debugger "steps out" of the current function call, that is, it resumes execution of the application until a function returns, and then passes control back to the debugger.
This command is sensitive to the debugger's selected call frame: it always steps out of the function running in that frame.
Consider this stack backtrace:
[-] Thread 1: "Master thread"
[+] -- presto ()
[+] -- allegro ()
[+] -- moderato ()
[+] -- andante () <<<<
[+] -- adagietto ()
[+] -- adagio ()
[+] -- largo ()
The selected frame is andante. Choosing Thread > Step Out resumes execution of the thread until andante returns.