To describe autumn using pictures in Engpsh, you could say:

The leaves are turning golden and red as the temperatures cool down.
The air is crisp and refreshing, perfect for taking a stroll through the park.
The trees are shedding their leaves, and the ground is covered in a blanket of color.
Harvest season is in full swing, with pumpkins, apples, and other autumnal fruits and vegetables ripe for the picking.
The sky is often clear and blue, with a cool breeze blowing through the air.

You could also use specific vocabulary related to autumn, such as "fall," "autumnal," and "harvest," to describe the season in your pictures.