Welcome to the IEEE SPS Seasonal School on Explainable AI and its Applications to Biometric Signal Processing! This program offers a unique opportunity to explore the intersection of advanced AI techniques and the analysis of biometric data. Through expert-led discussions and interactions, the participants will gain valuable insights into how explainable AI can enhance the transparency and trustworthiness of biometric signal processing, paving the way for more accurate, interpretable, and ethical AI-driven solutions in fields like healthcare, security, and personal identification. This seasonal school aims to give the participants hands-on experience, right from the foundations, from some of the leading experts in the fields in the areas of Explainable AI (XAI), Biometric Signal Processing, advances in deep architectures and applications using different modality of data.