The literature review is both a process and a section of a research paper in the social sciences. There are two stages.
Let's talk process first. Once you have developed a research question, the next step is to find what others have done to answer this question. This is where researching really begins. You will find readings that argue or claim what causes phenomenon or how to solve problems. You will also find writings where researchers are trying to measure and compare different phenomenon.
So, the literature review at this stage is diving into the existing debates on the topic and learning the various schools of thought, arguments, etc. The research question is your anchor here. If you find something that doesn't help answer your question, you don't have to read it. That's the power of the question format, it helps you filter what to read and what to ignore.
Now onto writing a literature review. A well written literature review is an art form: a complex entity performing many tasks simultaneously. First, when you write the literature review, you need to explain to your reader who has come before you (i.e. what have other scholars said about this topic/question). We do this to provide an overview but also to help the reader start to see the "camps" or "sides" within a debate. So a good literature review is factual, but is also a narrative helping your reader understand who studies the topic and their arguments. That means you organize the scholars into some kind of grouping. For example, you can group scholars by how they answer a research question. You can also group them by field of study. You can also group them chronologically. You can organize the groups in whatever manner you choose, just group them.
Second, your literature review must tell your reader where you stand in the debate. Do you think one school of thought has the best answer? If so, explain why. Do you think a predominant notion on the topic is really, really wrong? If so, tell us why. Are there gaps that previous scholars have missed and you can see them bright as can be? If so, explain why. This is where the literature review helps your reader determine how you situate yourself in the on-going debate. Your critique of the research is your "value-add." Also, your determination of what has come before will shape the methodologies you choose for the rest of your research paper (i.e. if you think the answer for why young people smoke is because of rebellion culture, then you will likely choose a method that lets you look at culture. If you think the reason is weak impulse control due to immature brain development, your method would look at psychological methods.)
Literature Review example - Here's an oral articulation of Evan Mandery's literature review of whether the death penalty deters violence in a NPR Fresh Air interview. Listen to minutes 33:00 - 34:50.
The corresponding footnote he mentions in his 2013 book, A Wild Justice, is from Chapter 14, "Proving Deterrence and Rationality." The footnote begins on page 474 and continues through page 482: