How long does it take to become a pilot

[Hakan G]

Hi! I’d like to ask if anybody here is a professional pilot? Because my son is absolutely passionate about airplanes and airports (his 14 years old now), so I wonder how long does it take to become a pilot of passenger airlines, in order to not miss the point when the professional education should start. I imagine it should take some time because it takes a lot of responsibility to be a pilot.
Also if anybody knows how much would it cost to have such an education? :livre

Thank you