If you were on a planet that takes 1,000 earth years to make a single orbit, then your "year" is 1,000 earth years. If you were to look at the earth and claim it was 5,000 'years' old, then we would measure it at 5 million years. If your planet takes a million years to make a single trip around its sun, then the earth is 5,000 years old.
Let's suppose that you were a being that measured 'years' in the time it takes your GALAXY to make a single revolution (a 'galactic year'). In the case of the Milky Way, it takes about 250 million years to make one revolution. If God bides His time in galactic years, and He measures our earth at 5,000 years old, then the earth (and the universe), are MUCH older than science has ever dared presume!