when you put "el" before the infinitive usually you want to speak about the action in general..so, "el correr es bueno para la salud" = running is good for health; but be careful in the case of " el ser.." could meaning about the soul of a person..." el ser de una persona es su esencia misma". I hope I have helped you.Bye

"es decir" could be translated to English as "that is" or "that is to say"

By adding "el" you convert it into a noun and can treat it as such. "Lo enojón" would be "your bad mood" or "his bad mood".

El ser = The being Es decir = Which means Greetings!