ένα

In a sentence

• Αγόρασα ένα βιβλίο.

  I bought a book.

  In this sentence, "ένα" is used as an indefinite article preceding a singular, masculine or neuter noun "βιβλίο".

• Βρήκα ένα ευρώ κάτω από το τραπέζι.

  I found one euro under the table.

  Here, "ένα" works as the numeral 'one,' specifying the quantity of "ευρώ" found.

• Το παιδί μου ζήτησε ένα παιχνίδι.

  My child asked for a toy.

  In this example, "ένα" functions as an indefinite article applied to the noun "παιχνίδι" to denote an unspecified single item.