Does the second attack from the Dual Wielder feat require an additional action, or a bonus action, to carry out?


I am looking at taking the Dual Wielder feat (PHB, p. 165), but I am not entirely sure as to how it works specifically. It includes the following benefit, among others:

You can use two-weapon fighting even when the one-handed melee weapons you are wielding aren’t light.

Does this second weapon attack require an additional action, or a bonus action, to carry out?