1
general::
A person, thing, or event that is quite remarkable, as in That pitcher is something else, or Her new film is something else. The else in this idiom means "other than ordinary." [Colloquial; early 1900s]
American Heritage Idioms
2
general::
Phrase(s): something else (again)
something entirely different. • Borrowing is one thing, but stealing is something else. • Skindiving is easy and fun, but scuba diving is something else again.
McGrawhill's American Idioms And Phrasal Verbs