。
She's super energetic.
Literal
[topic-は] tremendous energetic.
This sentence omits the copula だ that would normally cap a な-adjective predicate (元気 functions as a な-adjective here) — a casual, often feminine-flavored truncation common in conversational and journalistic Japanese. The omission gives the sentence a punchy, exclamatory feel. ものすごい元気 stacks the intensifier ものすごい on 元気 ('energetic, lively, in good spirits').