Simple.....
She has some regrets about not spending more time with her grandfather.
This being said because, she says, "[...]my favorite relative was my mother's father[...]." He was her favorite relative. The story then continues saying..."Still, i did not talk to him as much as I could[..][he always encouraged me to enjoy life. Now, Abuelito is long gone-he died over 20 years ago].
The story then ends with the narrator saying.."I wish I knew more about his life." Wistfully wishing she could go back..and spend more time with her grandfather.
(Abuelito means Grandpa)
Thus, your answer.