O que significa "leap" em Sherlock by Arthur Conan Doyle?

Hello Folks,
I was watching a British soap opera called ''Sherlock'' which is based on the masterpiece books created by Sir Arthur Conan Doyle,and all of sudden I faced a scene beetwen sherlock and dr watson which has one word that I couldn't tell the meaning. The word it's Leap. As in :''Wasn't a difficult leap'' I could tell immediately from the context that It's like a guess that wasn't difficult to make. Am I right?
What the meaning of this word or expression?

Thanks in advance