Hubble constant has 2 different meanings across 2 categories:
(cosmology) the ratio of the speed of recession of a galaxy (due to the expansion of the universe) to its distance from the observer; the Hubble constant is not actually a constant, but is regarded as measuring the expansion rate today
a number that expresses the rate of expansion of the universe; the velocity at which a distant object is receding from the Earth divided by its distance; its reciprocal gives the age of the universe