This is the 4722nd most frequent Turkish word.
dağa
"Dağa" means "to the mountain" in English.
In this sentence, 'dağa' is in the dative case, indicating motion towards the mountain.
Ahmet dağa tırmanıyor.
Ahmet is climbing the mountain.
Here, 'dağa' specifies the direction or destination, again implying movement towards the mountain.
Ali piknik için dağa gitti.
Ali went to the mountain for a picnic.
The word 'dağa' in this context also illustrates a sense of direction or target of the action.