The orbit of a moon, star or planet describes the trajectory of the object and usually refers to a path that repeats due to Kepler's laws of planetary motion.
In galactic dynamics, we often refer to the orbit of a satellite galaxy or star and mean the path that it takes.
In atomic terms, we often refer to the "orbit of an electron" as we find it easy to visualise in analogy with the Sun and planets. The modern quantum mechanical paradigm suggests this is over-simplified, and we should not think of electrons as ever in a specific time or place when bound to an atomic nucleus.
The orbital period of a planet or star can be computed by knowing the masses and separation of two objects.