The further away in the universe something is the faster it is traveling away from us. Fast things experience something called redshift and this makes the object appear redder. Eventually, when something is so far away it gets even redder than red and becomes infrared. This is why JWST can see further than any telescope we've had before.
Light takes time to travel to us, so the furthest away objects are also the oldest. Telescopes like Hubble and JWST look back in time. JWST can see further than Hubble because it is in the infrared so it can look almost to the beginning of the universe, 13.7 billion years ago.