A Glacier Bay faucet has a cartridge valve in each faucet handle. A double-handled faucet has two cartridges while a single-handled faucet has just one.
To replace a cartridge:
Turn off water to the faucet, remove the rubber cap on the faucet's handle, unscrew the handle and remove it from the faucet.
Unscrew and remove the adapter on the handle. Unscrew the retaining nut at the base and pull out the old cartridge and replace with a new cartridge.
Rebuild the faucet by reattaching the retaining nut, adapter and rubber cap. Repeat the steps for a two-handled faucet.