Grafting is the process of taking one plant and binding its stem to that of another so that they grow together.
Why? Because with a grafted plant will fruit sooner, and bear more fruit.
The 'scion', or fruiting part, pictured, is cut from a mature tree, then bound onto the cut stem of a young rooted tree.
Teaching villagers this skill means their tree produce more fruit for food and sale sooner - a remarkably easy, effective technique.