I am trying my best to learn everything about the tools as i go along. At 5:41 you press E to make the loop cut even. Can ...

I am trying my best to learn everything about the tools as i go along. At 5:41 you press E to make the loop cut even. Can you please explain what that does? On my model it doesn't make the loop cut even, it looks better without pressing E. Thankyou!