On-the-job training means that you learn how to do your job while you are working. Just like when you are learning how to play a new game or ride a bike, you need help from someone who already knows how to do it. At your job, your boss or another experienced person teaches you how to do your work step by step, so that you can get better and better at it. This way, you can practice the skills you need in real life situations, with actual customers or projects. It's like having a coach or a teacher who watches you and gives you advice, so that you can improve and become more confident in what you do. With on-the-job training, you can acquire new skills and knowledge, get feedback, and make mistakes in a safe and supportive environment, until you become an expert in your field.