A heliographic chart of the orbits of Mars and the Earth showing the relative positions of both planets. Quadrature is when Mars is directly east or west of Earth as shown.
Image source: Association of Lunar and Planetary Observers (ALPO).

Mars has reached eastern quadrature for its 2020 apparition. Quadrature is when a celestial body due to elongation, appears perpendicular to the direction of the Sun. This is a concept that allowed Copernicus to state which planets are farther from the Sun than Earth.

A very detailed explanation of Mars’ apparent motions in our sky may be found here.