Actually... let me illustrate as best i can in this currently 2 dimensional space...

this is one dimension:

.

a point in space.


This is 2 dimensions:

.__________________________________.

a line between 2 points.


This is 3 dimensions:

.__________________________________. your nose

2 points in space and the distance to your nose.


Now, if a sentient creature exists in 2 dimensional space, he would indeed experience 3 dimensional space even though he cannot actually fully take part in that 3 dimensional space. What he would see as he viewed 3 dimensional things from his 2 dimensional space, are simply more lines, lines upon lines upon lines, without having the perception of distance or height, volume. He would perceive only that part of the 3rd dimension that intersects his 2 dimensional plane. and he would perceive it as 2 dimensional just like his own space even though from my 3 dimensional perspective it actually is much fuller, much more than just that.

I could add a 4th dimension to this post and the distance to your nose simply by adding a theme song. you couldn't see the music or measure it with a ruler but certainly you might enjoy it, or not, assuming you have working ears to hear sound.