Hi, the lower before graph line shows that you have a loss of sensitivity in the low frequencies i.e the Bass sounds.
The after line graph shows what the Note 2 will do, to amplify or boost these lower frequencies i.e Bass sounds, so that you can better hear them.
Most peoples hearing is not perfect for either right or left ear.
I have used this built in adjustment before with a pair of Bose QC15's, and it has worked fine letting me hear my music better using the inbuilt Note 2's music app.
Yes I have a bit of a hearing loss, and I wish other phone or audio manufactures included adjustments like this in their products. As stated before not everyones hearing is perfect.
But allowing these adjustments would go some way in better enjoying their products more.