。
She's Betty.
Literal
She [topic-は] Betty is.
As basic as Japanese sentences get: 彼女 + は + name + です. ベティ is the standard katakana transcription of the English name 'Betty' — short i becomes イ, voiceless t stays t, final y becomes イ. Names like this are common in textbook material. The sentence is fine as a teaching example but unmemorable on its own.