u ta da hikaru
宇 多 田 光

this is her name written in Japanese, though you often see her first name, Hikaru, in katakana: ヒカル.

宇 means heaven, roof, house, eaves, or counter for buildings
多 means　frequent, many, much
田 means rice field, rice paddy
光 means light


about 田. In names I've heard it is more used as phonetical than actually use the meaning "rice field".

However, the above is only the kanji explanations. The name Utada in this case I don't think mean anything. Not even in Japan... It's just phonetical, as far as I know :o