An easy way to remember which side of the ship is port or starboard (besides just remembering that “starboard” came from the steering oar placed on the right side of a ship because most people are right handed) is just to remember that a ship at sea has “left” port. Another one is “Star light, star bright, starboard is on the right”.
The word “port” comes from the Latin “portus” meaning “port/harbor”, which before that meant “entrance, passage”. This in turn comes from the Proto-Indo-European “*prtu”, meaning “a passage”.