What does ‘capillaries join up to form veins which empty into the heart’ mean ?

The capillaries join up to form larger vessel which in turn forms veins The veins carry blood back to the heart The veins are under less pressure than the arteries. Veins have no pulse and are formed nearer to the surface than arteries. Capillaries Arterioles divide repeatedly to form a network penetrating between the cells of all tissues of the body. These small vessels are called capillaries. The walls are only one cell thick and some capillaries are so narrow that red blood cells have to fold up to pass through them. Capillaries form networks in tissues called capillary beds. The capillary networks in capillary beds are so dense that no living cell is far from its supply of oxygen and food.