This character wears clothing with small pieces of fabric sewn together. In other words: A patched-up clothing.
Either distinctively sewn messy, clothing that seems to show visible sewn threading combining pieces of fabric are patchwork.
Formal patchwork clothing also exist, often carefully sewn in patterns.
In terms of the actual sewing technique:
Patchwork or "pieced work" is a form of needlework that involves sewing together pieces of fabric into a larger design. The larger design is usually based on repeating patterns built up with different fabric shapes (which can be different colors). These shapes are carefully measured and cut, basic geometric shapes making them easy to piece together.