Translation:She is the best teacher in our village.
It only means the best teacher in the village. 'Lerares' is used simply because she's female. Sometimes they can accentuate the gender, for example here: hij is de beste verpleger (He is the best nurse) you can only know he's the best nurse, no stress is put on the gender. But in this case: Hij is de beste mannelijke verpleger van ons dorp (He's the best male nurse in our village), you can assume that the stress is on the 'male'. But you can only know that from the context.