Questions concerning social security wages/tax and medicare wages/tax

I saw them in box 3, 4, 5 and 6 and don't know whether they come from. I would like to ask
(1) Do I actually enjoy social security wages and medicare wages? I don't think I have received that amount of money from my paycheck. If still I do, then when and how I can enjoy the benefit of these wages?
(2) does the social security and medicare tax comes from my wages in box 1 or from box 3 and 5?