。
She really wants to know the result.
Literal
She [topic-は] that result [object-を] very wants-to-know-is-displaying.
When attributing 'wanting to do' to someone else (third person), Japanese requires ~たがる rather than ~たい. 知りたがる literally means 'displays signs of wanting to know'. The form attaches to the masu-stem (知り + たがる), and the result inflects as a regular う-verb. The ~ている here marks the current ongoing display of that desire — 'is in the state of showing she wants to know'. This third-person desire restriction reflects a broader pattern in Japanese: you can't directly assert another person's inner state, only the outward signs of it.