Qualitative research and mixed methods research take many forms. Broadly speaking, they involve the collection and analysis of unstructured data, such as interviews, articles, social media content, open ended survey questions, etc. Qualitative data analysis software, like NVivo, can help you organize, analyze, and find insights in your unstructured data.
The TriCollege libraries have many books on qualitative research in general, including several that address NVivo in particular.
This article gives a contextual example of how NVivo can be used in the qualitative research process:
Welsh, E. (2002). Dealing with Data: Using NVivo in the Qualitative Data Analysis Process. Forum Qualitative Sozialforschung / Forum: Qualitative Social Research, 3(2). Retrieved from http://www.qualitative-research.net/index.php/fqs/article/view/865/1880
There is also a more general TriCollege research guide on Qualitative Data Analysis: