This is the 14390th most frequent Russian word.
отправляться
"To depart" or "to set off."
Here, 'отправляться' describes the train's scheduled departure, indicating a specific time.
Поезд отправляется в шесть утра.
The train departs at six in the morning.
This usage of 'отправляться' relates to the immediate action of leaving or setting out for a walk.
Мы отправляемся на прогулку прямо сейчас.
We're heading out for a walk right now.
In this sentence, 'отправляться' is used to indicate departing or starting a journey.