What is meant by routines in C++?

[ZahoorKhan]

http://s7.postimg.org/czzvwe2ez/image.png 

Can you explain me that is meant by routines and what is linker in C++?

[mutexe]

http://stackoverflow.com/questions/3322911/what-do-linkers-do
http://www.lurklurk.org/linkers/linkers.html