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Please tell me the expected time of arrival.
Literal
Scheduled arrival-time [object-を] tell-[polite-てください].
予定到着時刻 is a four-element noun compound (予定+到着+時刻) — 'scheduled/expected arrival time,' essentially 'ETA.' Japanese stacks nouns in such compounds with far less friction than English; recognizing the pieces (予定, 到着, 時刻) makes the whole decomposable. 時刻 is 'clock time' — more precise than 時間 ('duration / time in general').