A literature review is a paper in which the author provides a critical overview of current research on a topic. Often, literature reviews are organized thematically, but what themes emerge will depend on your research question and how research on this question or topic is done.
Conducting a literature review requires gathering a large number of sources, then selectively evaluating them to see which ones are worth discussing and including. Identifying the research question, methodology, conclusions, and limitations of sources as you read it will help you compare and contrast them within your paper. It is also important to try to identify gaps in the existing research, or possibilities for future research on this topic.