"People are like, 'Well, she doesn't know the Sex Pistols.' Why would I know that stuff? Look how young I am. That stuff's old, right?"

Avril Lavigne is making a point about how her age need to not be a factor in determining her understanding of particular topics. She is stating that individuals need to not expect her to learn about the Sex Pistols, as she is young and the band is old. She is indicating that her age ought to not be a consider identifying her understanding of certain topics, which she should not be evaluated for not understanding something that is outside of her generation. Lavigne is likewise making a point about how age ought to not be a consider figuring out someone's understanding, and that individuals ought to not be evaluated for not knowing something that is beyond their generation. She is suggesting that knowledge must be judged by itself merits, and not on the age of the individual who has it.