If design language is something completely new for you, you should first take note on how other artists use shapes. Check sites for inspiration, and break down the compositions you like into simple shapes. Think about which shapes seem to be the most noticeable or common and why.
Unless you’re aiming for strong minimalism, your design will have multiple elements. This will force you to work with different shapes at the same time.
This is where visual hierarchy comes in
If you’re going for a specific meaning, you need to make sure that the appropriate shape is front and center of your design. As a result, their importance outshines that of the other shapes sometimes necessary for compound shapes.