How to Hack Any One Not on LAN.

Hi all xile hackers,

Hell a lot of tools are available for us on kali to hack a PC, hack an account or hack a phone etc.. but the problem is all the above mentioned things can be said to be working only over the connections on our own LAN.My friend are also saying that Metasploit and SET,Beef etc only work over our LAN so not pretty much useful,but i am damn sure they can be made to work over WAN using some so called port forwarding etc..

I am not much into port forwarding etc..can some one explain what is port forwarding,how does it work and how to make Metasploit,SET toolkit and Beef etc.. work over Wan..