。
She can hardly wait for the holidays.
Literal
She [topic-は] break [object-を] is-waiting-impatiently.
待ちかねる is a compound verb pairing 待つ ('to wait') with the auxiliary ~かねる ('to find difficult / unable to'), producing 'to be unable to keep waiting / to wait impatiently.' The literal logic — 'cannot wait' — captures English 'can hardly wait' precisely. ~かねる is one of those small auxiliaries that punches above its weight: 言いかねる ('hesitate to say'), 信じかねる ('find hard to believe'), 我慢しかねる ('cannot endure'). The ~ている form here keeps the impatience as an ongoing state.