What does it mean when your breaks go all the way to the floor and you hear loud

COULD BE A LEAK IN BRAKE SYSTEM OR PADS ARE COMPLETELY GONE A STEEL PLATE IS CONTACTING ROTOR.TOW TO A SHOP FOR AN INSP

I had the same problem, mechanic told me could be the brake cylinder, he managed to detect the problem. there was to much air in the brake system. So he oped all the tires and asked me to push the brake puddle 10 times and push once all the way down and hold for few second to kick the air out of brake system. we did this on each tire brake. This did really worked, and brake went back to normal, puddle is stiff and strong, brake also stops promptly. try it and hopefully it will work. First you should have new brake pads and than apply this Good luck..!!