This is the 735th most frequent Turkish word.
işe
"İşe" means "to work" or "to the job/work" depending on the context.
Here 'işe' denotes 'to work' and is used as an indirect object in the sentence to indicate movement towards a workplace.
Bugün işe erken gitmeliyim.
I need to go to work early today.
In this sentence, 'işe' again refers to 'to the work', indicating a transition towards beginning a task or work.
Kadın işe başlamadan önce kahve içti.
The woman drank coffee before starting the work.
Here 'işe' is used abstractly, meaning 'to work,' and follows the verb suggesting a conceptual relation to work.