Imagine you're at the park with your friend, and you both have a sandwich for lunch. You both like your sandwiches a lot, and you feel energized after eating them. When you're finished, your friend says to you, "I am the bread of life." That might be a bit confusing, right?
That's pretty much what Jesus said to the people who were listening to him one day a long time ago. He had just fed a whole bunch of people with some fish and bread, and they were all amazed. So then Jesus told them that he was the bread of life, and that anyone who ate his "bread" would never be hungry again.
But he wasn't talking about real bread you eat for lunch. Jesus was using bread as a symbol for something bigger. He was talking about how if you believe in him and follow his teachings, you will feel fulfilled and satisfied in your heart and soul. It's like he's saying that he's the source of all the good things people need to live a happy, fulfilling life.
Jesus wasn't just talking about his own physical body being bread either. He was talking about how his teachings and his love can feed people's spirits, and give them the strength and guidance they need to live good lives.
So when people talk about the "bread of life discourse," they're talking about the conversation Jesus had with his followers about how he is the source of all the good things people need, and how following him can satisfy people's deepest needs and desires.