This is the 4658th most frequent German word.
unzählige
Countless.
Here, 'unzählige' is used as an adjective describing 'Sterne' (stars) to express a large, indefinite amount.
Unzählige Sterne funkeln am Nachthimmel.
Countless stars are sparkling in the night sky.
In this sentence, 'unzähligen' is an adjective modifying 'Versuchen' (attempts), emphasizing a large number referring to repeated efforts.
Nach unzähligen Versuchen gab sie schließlich auf.
After countless attempts, she finally gave up.
Here, 'unzählige' acts as an adjective for 'Möglichkeiten' (possibilities) indicating an indefinite variety of options.