The airplane departs from Heathrow Airport at 12:30.

Literal

Airplane [topic-は] 12:30 [at-に] Heathrow-Airport [from-を] departs.

ヒースロー is the katakana rendering of 'Heathrow.' The を with 出発する marks the departure point. 半 (はん) means 'half' and is the standard way to say ':30' in Japanese time expressions: 12時半 = 12:30.