Screeching in right rear wheel ,sound stops when breaks applied

Have the brakes checked out. It could be way past time for brake replacement.

[Disc brakes have a piece of metal attached to the brake pad, that when the lining of the brake pad is worn down to the replacement level, the metal touches the brake rotor. {Actually the metal is part of the Brake Pad Inner Shim, for a 2006 Kia Sedona}

There is a metal to metal screeching sound. A sign that the brake pads need to be changed Pronto!

(If it isn't taken care of as soon as possible, that piece of metal will score {Cut} the brake rotor. This could lead to where the rotor cannot be safely turned on a brake lathe, and the rotor will have to be replaced.

Rotors cost a Lot more, $$$$$ than simple brake pad replacement!)

If your Sedona has drum brakes in the rear, the lining of the brake shoe has worn down to the metal backing, and now there is metal to metal contacting. (Instead of brake shoe lining to metal drum surface)

Again, a screeching sound may be produced. This situation warrants immediate attention! The brake drum can also be turned by a brake lathe, but it is just like a brake rotor for a minimum thickness that it can be lathed to.
(Cut to)

Brake rotors resemble a flat disc, and there is a minimum thickness that they can safely be cut, (Lathed), down to.
Brake Drums resemble a round cake pan, and the outside thickness can only be cut, (Lathed) out so far. (Minimum thickness for safety.
Either Drum Brakes or Disc Brakes were offered on the 2006 Kia Sedona.

Do you have rear disk breaks? could just be your squeeler telling you its time for new pads. is so dont get hard pads put in. sure they tell you they last longer, and they do. but your rotors will go quicker, and they cost more.

Its the brake pad wear indicator telling you your pads are in need of replacing