Ruby is an object-oriented language with a strong focus on developer productivity, designed to make coding easier and more enjoyable. Its dynamic typing allows for flexible and modular code, making it well-suited for web development frameworks like Rails. MongoDB, a document database, can be used with Ruby to overcome the object-relational impedance mismatch, which is typically addressed by relational databases using Active Record. Gems like Mongoid and MongoMapper provide an interface between Ruby and MongoDB, allowing developers to use MongoDB as a NoSQL datastore with Rails. The 10gen Ruby driver also enables direct interaction with MongoDB from Ruby code. With its ease of use and flexibility, Ruby is well-positioned to take advantage of the benefits offered by MongoDB, making it a popular choice for web development projects.