Sounds like the rear pads or shoes are worn, and you have metal to metal contact. Inspect the brakes asap

Usually, the brake high-pitched sqeal is the disc pad wear sensor contacts the brake rotor - giving an audible warning about the pad thickness - getting thin and time to replace.
Try the many on-line auto parts sources; such as - www.autopartswarehouse.com, www.partsgeek.com or www.rockauto.com for the replacement parts.

See this How to Bleed Brakes

FAQ and Step-by-Step Instructions

http://www.zeckhausen.com/bleeding_brakes.htm

Several possibilities; leaking brake fluid from the system; front brake calipers / hoses, rear wheel cylinders, flexible hoses. May also be loss of fluid from the brake master cylinder. Cannot tell for certain without a thorough inspection.

The picture you show is a pressure differential valve . Brakes apply about 60% to the front tires and about 40% to the rear . The master cylinder puts 100% to this valve . Then the valve splits it to the front and rear . Can't tell by the picture what or where it is leaking but no matter what it shouldn't leak at all .

Several possibilities; leaking brake fluid from the system; front brake calipers / hoses, rear wheel cylinders, flexible hoses. May also be loss of fluid from the brake master cylinder. Cannot tell for certain without a thorough inspection.

may be the master cylinder is loseing presure and needs to be replaced or needs a rebuild also check for leakes under your vehicle

Try a penetrating oil or spray to soak the frozen pistons. In the long run, it may be less expensive simply to replace the frozen calpiers. Try the many on-line auto parts sources, such as; www.autopartswarehouse.com or ww.rockauto.com for the replacement parts.

Have you checked / replaced the front wheel bearings / hub assemblies - due to wear? The other possibility is the front disc brake rotors are warped - fairly common. If the front rootors are replaced, they are fairly inexpensive; try the many on-line auto parts sources, such as; www.autopartswarehouse.com or www.rockauto.com. They (Rock Auto) list the front brake rotors from around $14.00 each for your vehicle.

Did you bleed the entire brake system - and not just the left front caliper? Remember that the residual air can migrate into the entire brake system causing the low pedal condition.
Try bleeding the entire brake system - beginning with the wheel furthest from the master cylinder.

u r talking about the brake light on the dash correct//ok if so then u have either a stuck emer brake that has not released or u have air in the brake line or in the braking system, have u had any service done lately check ur brake fluid could b low

Front or rear ? Jack it up and take one tire at a time off and look at the brakes . The front wear at 60% And the back wear at 40% give or take a bit . Might just be time for a brake job . They don't last forever .

A sticky caliper mechanism could hold hold pads against rotor longer after releasing brakes is one possibility.

yes replace the pads. if it were my vehicle I would use genuine Kia pads.

Cannot assume that you checked it correctly. At the brake light switch there is two wires, an orange and the other is a blue. The orange has to have battery voltage at all times, the blue has battery voltage when the brake pedal is depressed. If the orange has no battery voltage, check the 15 amp fuse labeled STOP LP located in the interior fuse panel. Confirm the details so I can continue if needed.

do you have voltage at the bulbs? get a wiring diagram and check which fuse is for the brake light, use a voltmeter to find out where is the problem..can be a missing fuse..