Helen is describing her life before and after her teacher Anne Sullivan came as two different lives.
Helen Keller was born with sight and hearing, but lost them at a very young age. This made her life very dark and difficult during her early childhood. Anne Sullivan taught her the names of things and how to read and write. This was a remarkable difference.
Hellen describes the first time she met Anne Sullivan.
I felt approaching footsteps. I stretched out my hand as I supposed to my mother. Some one took it, and I was caught up and held close in the arms of her who had come to reveal all things to me, and, more than all things else, to love me. (Ch. 4)
Hellen describes two different lives because before Annie Sullivan came to teach her, she lived a life of darkness and ignorance. Her parents did the best they could, and Helen was very smart, but they could not teach her to talk or read in the traditional way. The world was very closed-off to her.
Anne Sullivan wasted no time in starting to teach Helen words.
The morning after my teacher came she led me into her room and gave me a doll. … When I had played with it a little while, Miss Sullivan slowly spelled into my hand the word "d-o-l-l." (Ch. 4)
Through determination and creativity, Anne Sullivan managed to get through to her young student. She had to help the Kellers overcome many bad habits of indulging and babying Helen. Helen made great strides very quickly, even though she had never been able to learn before. When Anne finally succeeded in teaching Helen the word for “water,” it opened the floodgates for many other words, including “teacher.” Helen was very happy. She had the gift of language.