Revolution
Revolution is the motion of one body in orbit around another, such as Earth traveling around the Sun once every 365.25 days.
Definition
Revolution is when one object travels all the way around another object: Earth revolves around the Sun, the Moon revolves around Earth, and one complete revolution of Earth around the Sun takes one year. More precisely, revolution is orbital motion under gravity, and the time for one complete trip is the orbital period; Earth revolves once every $365.25$ days at an average speed of about $30\ \text{km/s}$ along a nearly circular ellipse. Combined with the tilted axis, this motion produces the yearly cycle of seasons and the changing constellations seen through the year. The motion is governed by Kepler's laws and Newtonian gravity: the body follows an ellipse with the primary at a focus, sweeps equal areas in equal times, and has a period given by $T^2 = 4\pi^2 a^3 / G(M + m)$. Strictly, both bodies revolve around their common center of mass, the barycenter, which for the Earth-Moon system lies about $4{,}670\ \text{km}$ from Earth's center, inside the planet. The sidereal period is measured against the stars and differs from the synodic period measured against the Sun.
Example
Earth revolves around the Sun once every $365$ days, and the Moon revolves around Earth once every $27$ days or so. Because Earth moves about $1^\circ$ along its orbit each day, a given star rises about $4$ minutes earlier each night, and after six months of revolution the night side of Earth faces the opposite part of the sky. The Moon's sidereal revolution period is $27.32$ days, but its synodic period, one full cycle of phases, is $29.53$ days, because Earth's revolution around the Sun means the Moon must travel farther to return to the same Sun-Earth-Moon alignment.
Key Insight
Do not mix up revolution and rotation: revolution is going around something else, as Earth does around the Sun, while rotation is spinning in place on an axis. Earth's revolution does not cause seasons by itself; if Earth's axis were not tilted, revolving around the Sun would produce no seasons at all. Revolution is measurable from Earth through stellar aberration and annual parallax, the tiny shifts in star positions caused by Earth's changing position and velocity. Those effects, first measured in 1729 and 1838, were the direct proof that Earth moves.