how has the second amendment impact the average citizen today

It really depends on what you would call an “average” American citizen.
An estimated 42% (see source below) of households own a gun, but a “household” includes more than one person, so a significantly lower percentage of people in the U.S. actually own a gun. The percentage of people who actually own a gun could be as low as 33%, but isn’t known exactly.
For this minority, the Second Amendment makes it legal for them to carry their firearm. In some states, additional rights—like so-called “open carry” laws—extend this right and allows these people to carry their gun with them in public.
However, for the majority of Americans, the Second Amendment actually puts them at risk, because, with more guns around, they are far more likely to die or get seriously hurt in a gun crime, intentionally or accidentally.
https://edition.cnn.com/2018/02/15/politics/guns-dont-know-how-many-america/index.html