Impulse is a change in momentum. Hence, the SI unit of impulse is Ns.
What is the impulse?
A large amount of force acting on an object for a short time interval is called impulse or impulsive force. Numerically impulse is the product of force and time. The Impulse of an object is equal to the change in momentum of the object. The product of the force & the time for which it acts on a body is called the impulse of a force. The force acting on a body for a short interval of time is called impulsive force.