My wife was driving and noticed the brake pedal goes to the floor?

Hello,

There are several reasons for the brake pedal to got to the floor.
The pedal goes to the floor when the brake system cannot generate pressure to the brake pads. It could be as simple as being low on brake fluid, it can also happen due to air in the brake system, a faulty brake master cylinder, due to a leak in the brake system.

Have a look at this guide, it covers the common reasons and remedies:

https://www.2carpros.com/articles/brake-pedal-goes-to-the-floor

If there is air in the system, it will need to be bleed. Here is a helpful article on how to bleed the brakes:

https://www.2carpros.com/articles/how-to-bleed-or-flush-a-car-brake-system

The brake master cylinder can have faulty seals on the inside and unable to create pressure.

https://www.2carpros.com/articles/how-to-replace-a-brake-master-cylinder

I have attached diagrams for your reference.

Please let me know of any questions.
Thank you.