Here's a simple metaphor for you.
Imagine you're driving. To move forward, you need to step on the accelerator.
And to slow down, you take your foot off the accelerator and optionally (depending on how quickly you need to slow down), you use that same foot to apply pressure to the brakes.
(I'm talking about combustion engine vehicles here, but I'm assuming it's the same with electric.)
What you wouldn't do: