This is the 119th most frequent Indonesian word.
sebuah
"A" or "an" (used as an article to denote a single, non-specific object).
In this sentence, 'sebuah' is used to indicate a singular, non-specific object, in this case, 'a book', which is common in providing a general statement.
Dia membeli sebuah buku di toko.
He bought a book at the store.
Here, 'sebuah' emphasizes a single item among many, highlighting the flower viewed in the garden.
Di taman, saya melihat sebuah bunga yang indah.
In the garden, I saw a beautiful flower.
In this case, 'sebuah' underscores a conceptual singular item, implying a singular specific response needed.