Mongo DB / Django? -- Can someone explain in essence what these are and why so prevalent?

If you've heard about Ruby on Rails, which is a framework for quickly getting a web app into production for the Ruby programming language, then Django is a similar thing for Python web apps. It takes a lot of the background processes out of the equation so that you can focus on your specific application instead of all of the things needed to make it web-ready. It takes care of many of the steps necessary to translate your idea to an experience that people can have in their browser.

MongoDB is a database management system that exists in a category called NoSQL databases. While MySQL, PostgreSQL, SQLite3, and other use the SQL querying language to structure records in a relational database, there are other strategies that are useful for other use-cases. MongoDB and many other NoSQL databases were created to excell in some areas that traditional SQL relational databases often fall short. They don't require a pre-planned data schema, use the concept of "documents" instead of tables and records, and can have built-in replication and sharding, which allow you to easily expand your data storage schemes to be highly available and fault tolerant. They are definitely something to look into, but like any other software choice, they are not a catch-all miracle solution. There are trade offs that you should evaluate.

Take a look at these two articles to learn about some of the differences between different SQL and NoSQL solutions.