If you have the Extra Attack feature and another feature that allows you to use your bonus action to make any number of additional attacks, you instead make those additional attacks as part of the Attack action (without using your bonus action).
You can do this once per standard action, and you cannot use any other feature that allows you additional attacks as either part of your Attack action or as a bonus action with the same standard action.
A "standard action" refers to the action any creature can take on its turn, including if given another "standard action" with features such as the Fighter's Action Surge.
But it doesn't refer to an action that has limits, such as the action of the haste spell.