Libgdx Render method

Libgdx Render method

I have a question on libgdx render method, I am currently designing a game
that requires me to draw different type of images to the screen upon the
user request. However I am having this issue where by the game screen will
get blank out after 4-5 tries, I realised the render method is somehow a
endless loop. So my question is how does the render method actually works
? need some explanation on that, had checked the documentation for it but
dont really understand.
Much help is appreciated, Thanks!!!
leDon