This is the 540th most frequent Turkish word.
sonraki
"Next" or "following."
Here, 'sonraki' is used as an adjective modifying 'durağa' (the stop) to mean 'the next' in sequence.
Bir sonraki durağa dikkat et.
Pay attention to the next stop.
In this sentence, 'sonraki' describes 'gün' (the day) to refer to the day following the current or mentioned day.
Sonraki gün toplantıya katıldık.
We attended the meeting the next day.
'Sonraki' is used here to modify 'dönemde' (in the period), indicating the period of time after a specific event.