The 'SPIN Selling Fieldbook' by Nirbhik Jangid provides practical tools and techniques for applying the SPIN selling model in various sales contexts. This model emphasizes four types of questions: Situation, Problem, Implication, and Need-Payoff, to effectively understand and address customer needs. The book guides sellers through the stages of a sales call and strategies for obtaining commitment from buyers, highlighting the importance of effective questioning and demonstrating capability.