Technique behind opening .exe files

actually there is a popular software on a net named resource hacker is available to easily change the f the start button name.In order to modify the start button name we have to open the explorer.exe in resource hacker software first and then we have to follow the steps.
My doubt arises here
how the resource hacker can able to open the .exe files .Actually what is the technical secrets behind this..plz tell it in a clear manner .I am requesting these things in order to remove the ignorance brothers