Which friend knows what tree this is? There are red beans on the leaves.

This is not a fruit, but a gall, which is a deformed structure formed by the stimulation of insect secretions and the accelerated division of cells in plant tissues. Bile has many shapes, usually capsules, spheres or cylinders. A gall is also a house made of insects. Larvae feed in it all their lives and pupate in it. After eclosion, they bite through the galls and look for plants to lay eggs. After hatching and feeding, the larvae form galls again. Aphids, scale insects, weevils, sawflies, gall midges, moths, etc. , can cause plant gall. Gall has no fatal harm to plants, but it will affect the growth and beauty of plants, leading to the slow growth of plants.