The most important things for Expressionism are:
Strong emotional expression: The goal is not to depict objective reality, but to convey the artist's subjective feelings, inner anguish, and insights.
Distorted shapes and unnatural colors: The objects and landscapes depicted are often criticized or reduced to basic shapes, and colors (such as the intense shades of red seen in the image) are used to emphasize the emotional impact in the direction of a purely realistic depiction.
Energetic brushwork: Rough, fast, and tense brushstrokes create movement and a restless feeling.