What does setTextMatrix of contentByte class in iText do?

Question

I am using iText and am very new to it. There have been several situations where I think I could have figured out the problem with my code if I knew what I was doing - I use examples without knowing the workings behind the code, and even as I look at the source I can't figure out what the programmer was thinking.

What does setTextMatrix of contentByteArray in iText do? And how do I figure out the parameter values I need?

For example:

cb.setTextMatrix(1, 0);