In Frankenstein, how does Chapter 5 help us appreciate the character of Victor Frankenstein?
I'm not sure I would include the word "appreciate" in your question. Chapter Five does show us an in depth portrayal of Victor, but in the end, it is not a very complimentary picture.
Victor's motivation for creating the monster seems noble. He wants to be able to create life and eventually bring back people who have suffered death. It's important to remember that the subtitle of this book is "The Modern Prometheus". Prometheus was a Greek Titan who, thinking his was doing man a favor, brought fire to mankind. Fire did indeed help humans but it also brought a form of destruction and death to mankind.
This parallels Victor's actions and personality. He realizes he is delving into secrets that should perhaps be left alone but he says in Chapter 3 that “how many things are we upon the brink of becoming acquainted, if cowardice or carelessness did not restrain our inquiries.” In his pride, Victor thinks he can handle whatever "cowardice or carelessness" that his inquiry brings. But the minute he succeeds in bringing the monster to live, he succumbs to that cowardice and runs away, not caring what happens to his own creation. He leaves his home, runs into Clerval, and basically forgets the creature that he is responsible for. Like Promethesus, Victor has unleashed something he meant for good, but his creation will bring disastrous consequences to himself, his family, and others.