The yellow block is a 'bleed block' which is a spacer which replaces the brake pads when bleeding brakes to keep the pads away from oil and to avoid over filling the system.
The white cylinder with o-ring is a funnel extension, which makes a funnel compatible with your road levers when bleeding the brakes (mtb levers don't need it).
The two metal pieces are often known as connector inserts, or barbs, which go inside the hydraulic hose when installing brakes or shortening hydraulic hose. They are essential to prevent crushing the hose. These are just spares. They would normally be found alongside brass olives which are also required to do these tasks.