[Noob Question] What is 'Cast to'

So i can’t get my mind on exactly what is a ‘Cast to’ in blueprints… I mean what is it for? What does it do exactly…

Also i have an example here where someone placed a Cast to node, but even if i remove the node it works fine… Can you tell me about that too?
Images - This is in Thirdpersongamemode, it takes a floor and spawns it and returns the position for placing the next floor... - Album on Imgur

Please use really simple words
I’m really thankful to you