First i'll just quickly mention that some of the functions you are using are sorta outdated, your just learning tho, so its not a big deal.

Anyway, Matrices are simply a mathematical tool to move points in a certain way. You can think of it this way. You can store rotations and/or translations inside of Matrices. Now Im not sure if you use shaders, but if you do this will be more obvious if you don't ill explain anyway.

A point is multiplied by (usually) multiple matrices in openGL to transform the point. For example a couple of matrix multiplications can turn a random point in 3D/2D space, to a point relative to your camera, to a point taking into account perspective (like changing the point to how it would look like out of a camera lens), and eventually to a point relative to your screen.

[edit: fixed typos]

Thanks, I haven't looked into shaders yet, so far I have trying to get the cameras working, and objects rotating the way I want.

I have seen camera objects in a tutorial (

http://www.java-gaming.org/index.php?topic=30871.0 ) that uses two Matrix4f objects named "projection", and "view". I would have followed that tutorial if It didn't had used the m variables inside the Matrix4f object, m00, m11, m22, m23, m32, m33 makes no sense to me, and I felt like just copy and paste the code wouldn't do me any good.

EDIT: Anyway, I think I'll read up on matrix later, and uses Vector3f for my camera/objects while i learning matrixes.