"A second father" is correct. Because Jimmy was a black man, "prejudice" most likely refers to racial prejudice.1. As I know, "a second" is different from "the second". Even if you make the fourth same miistake, your boss or father can forgive you, saying "I will give a second chance", right? So in this context, do they ususally say "a second someone(father)" for "another someone(father)" instead of "the second father"?
2. I don't know what "prejudice" he meant. Is it like racial one against African Americans or any type of broad concept of prejudice?
41)It was great for me to be out of the confined boarding school environment and I enjoyed being able to spend more of my free time outside and in nature. But the brighter spot during that time was the arrival of a 21-year-old black man my father hired to take care of (b) his new sailboat. His
name was Jimmy Brown. On the day I first saw him, little did I know that he would be one of the most important men in my life.
My father did not think about hiring someone for his new boat when he bought it, indeed. But soon, (d) he realized that the new boat was going to be a lot of work and decided to hire Jimmy after several friends recommended him as a capable handyman. It did not take long for Jimmy to prove
that my father’s friends were right about (e) him. My father trusted him more and more and allowed me to spend a lot of time with Jimmy.
Because of the time we spent together, we became really good friends. Eventually, he became like a second father to me. My father taught me many things, always showing (c)his interest in my education. But Jimmy taught me a lot more about nature. I loved every minute of the time I spent with him and he became one of my best friends. Because of my sincere friendship with him, I grew up without any prejudice.