Except for the Earth, each planet's English name is a Roman God's name.
Here are the meanings of the planet names.
Mercury: ROMAN GOD OF SPEED
Venus: ROMAN GODDESS OF LOVE
Earth:
Mars:ROMAN GOD OF WAR
Jupiter: KING OF THE ROMAN GODS
Saturn: FATHER OF JUPITER
Uranus: GREEK GOD OF THE SKY
Neptune: ROMAN GOD OF THE SEA
Pluto: ROMAN GOD OF THE UNDERWORLD
SUN: LATIN WORD FOR SUN: "SOL"
The English names for planets are mostly derived from the Romans, who took their names from gods and goddesses.
Because English has become the international language of science, we now take these names for granted. The majority of scientific journals are written in English. The International Astronomical Union (IAU), which assigns designations to celestial bodies, is based in France but conducts business in English. When it was founded, the IAU essentially adopted all of the English names for objects in our solar system.
The IAU now has rules for naming new celestial bodies that allow for a little more creativity than the parameters of the major planetary designations. After all, only a limited number of Greek and Roman gods, and we're discovering more and more stuff in space every day.