This is the 590th most frequent Indonesian word.
buah
Fruit.
Here, 'buah' is a classifier or quantifier for 'apel' (apple), used when counting pieces of fruit.
Saya makan satu buah apel hari ini.
I ate an apple today.
Here, 'buah' is used metaphorically to mean 'result' or 'outcome' of an endeavor.
Film ini adalah buah hasil dari kerja keras mereka.
This film is the outcome of their hard work.
In this case, 'buah' is part of the word 'sebuah', which means 'a' or 'one piece', used as a general classifier for objects.