"Beautiful sky" in Engpsh is "beautiful sky".

Source: The phrase "beautiful sky" is a common way to describe the appearance of the sky, especially when it has a particularly attractive or eye-catching appearance, such as a clear blue sky with white clouds, or a sky with a colorful sunset.

Example sentences in Engpsh with Chinese translation:

The sky was a beautiful shade of blue with just a few white clouds. (天空是一个美丽的蓝色，只有几朵白云。)
The sunset was stunning, painting the sky with beautiful hues of red and orange. (日落很壮观，用红色和橙色的美丽色彩涂抹天空。)
The city skypne was even more breathtaking with the beautiful sky as a backdrop. (城市的天际线因美丽的天空作为背景而更加令人惊叹。)