Why is it i hear air coming from the brake pedal and when i step on the brake pedal it stops

You have a blown power booster. It is leaking vacuum and you will have a hard brake pedal and find it tough to stop your vehicle. Replace the power booster and you will have brakes and no more leaking air sound.

That sounds more like a major leak or a bad master cylinder can you pump the brakes up to a hard pedal with the vehicle off?

sounds maybe booster is diaphram is bad

fluid is by passing rubbers in master cylinder . replace unit. noise if you are running engine could be air leaking from faulty booster unit

1. Check the fluid level in the reservoir after bleeding each wheel. Add DOT3 fluid, if necessary.
2. If the master cylinder was disassembled or if the reservoir becomes empty, bleed the air from the master cylinder as follows:
   1. Disconnect the brake lines from the master cylinder.
   2. Slowly depress the brake pedal and hold it.
   3. Block off the outlet plug with your finger, and release the brake pedal.
   4. Repeat 3 or 4 times.
   
   
3. Bleed the brake starting with the one furthest from the reservoir and then the next furthest, etc.
   
4. Depress the brake pedal several times, then loosen the bleeder plug with the pedal held down.
5. At the point when fluid stops coming out, tighten the bleeder plug to 11 Nm (8 ft. lbs.), then release the brake pedal.
6. Repeat until all the air in the fluid has been bled out.
7. Repeat the procedure to bleed the air out of brake line for each wheel.
8. Check the fluid level and add DOT3 fluid if necessary.

the brake booster is leaking vacum

you got it, the booster is leaking reducing the vacuum to the intake, replace it

This perfectly describes a failure of the brake vacuum booster.
Replace the power brake vacuum booster.

No such thing as vacuum lines to the master cylinder. You do have a vacuum line on the brake booster (power assist). When you step on the pedal do you hear a whoosing sound down by your pedal. This is a leaking Booster. Needs replacement.

When you step on the brake does the engine rpm change. This is a leaking check valve (one way air valve).

Is it possible that you are hearing the abs pump running in the engine compartment? It sounds like an ABS problem with one of your wheel speed sensors.