Mercury will be at eastern elongation from the Sun, which suggests the planet is east to the sun as seen from an observer on Earth making the angle of elongation. The planet can be best observed after the Sun sets, in the West direction.   

Elongation is generally defined as the angle between the two planets, or a planet and the sun, or a planet and the moon or the moon and the sun as seen by an observer on the Earth. Venus at elongation suggests the angle between Venus and Sun, and eastern elongation concludes the position of Venus in East of the Sun. Which means the Planet Venus is clearly seen after the sunset in the evening sky in the direction in which the sun sets i.e. west as seen from the Earth.