Translation: The kanji breaks down as such: first kanji "chi" means "earth, ground" which is the same kanji that is used in the word "chikyuu" which refers to the planet Earth. The second kanji "ba" translates to "location, place". Together, they form the the word "chiba" which, when the two kanji are placed together like this mean "local." The third "mamoru" litterally translates to "protector, guardian". So his name would be translated as "Local Guardian."

The kanji used for his name is yet another piece of evidence that points to him being the guardian of this planet. There's also the fact that Naoko-sensei confirmed that he takes the place of a Sailor Earth, but that's another story ^_~