Is this a ac three phase motor with a dynamic braking control?
That is a DC "braking" or "DC injection" braking circuit. Such a circuit is often called a dynamic braking or DC dynamic braking, but I think it is preferable just to call it DC braking. That avoids confusion with another type of braking that is called dynamic braking.

The circuit includes a variable resistor that is used to set the DC current applied to the motor windings. The braking current controls the braking torque. See: How much DC voltage is needed to brake a 3 triphasic motor? There is also a timer to limit the time that braking current is applied. Applying braking too long can overheat the motor.