The text discusses Nucleus, a tool from Scale that allows users to visualize and explore training data and labels for deep learning projects. It provides an intuitive web interface to identify potential flaws in ground truth labels and understand the relationship between data and model predictions. The authors demonstrate how to get started with Nucleus, upload a dataset, train a neural network, and compare model predictions to ground truth. They also highlight the importance of inspecting training data and model predictions to refine both the dataset and the neural network. Nucleus provides tools for filtering results, identifying failure cases, and annotating data labels, making it easier to develop effective deep learning projects.