The DevNet Sandbox is a cloud-based collection of labs designed for developers to explore, learn, and create solutions using Cisco technologies. It offers both always-on and reservation-based labs, featuring tools for collaboration, network simulation, and testing, as well as an Interoperability Verification Test (IVT) process for product certifications. Developers can access a variety of labs, enabling tasks from experimentation to integration testing, with many labs being free to use.