Figure out the meaning

"The Fifth Discipline Fieldbook"
What exactly <em>does</em> that mean?
<em>Does</em> that mean Academic book or something <em>else?</em>
 <em>I</em> <em>saw</em> this <em>expression a lot,</em> but <em>I</em> <em>couldn't </em>figure it out.
Can you explain it, please? because <em>I'</em>m <em>trying</em> to know the right meaning of it?
Thanks in advanced.

By the way, correct my note, please.

Hello<em> Ola, I tried to correct your notebook. It's maybe not the perfect correction, so write it in English notebooks to make natives correct your notebook. And if you want to know any word's meaning, ask a question, but in English questions too. good luck :)</em>