What do actors mean when they talk about 'baring their soul' on screen?

I've heard this phrase twice in less than a week. Shefali in her thank you speech after receiving the Zee Cine Award for best supporting actor in Gandhi my father said something to the effect of, '... am happy they acknowledged that it's hard work baring one's soul...' and then Nandana Sen talking about skin show in the forthcoming Rang Rasia goes '... baring the body is easier than baring the soul...' Now, what's this soul baring they are talking about? How could an actor who is playing some fictitious character on screen be baring his/ her soul? I wonder...