ما هذا؟
A Sprachzertifikat (language certificate) is a document that shows how well a person speaks a language. The language level is usually assessed according to levels from A1 (beginner) to C2 (advanced).
You can find more information here:
Sprachprüfungen und -zertifikate
من أين يمكنني الحصول عليه؟
If you pass a language exam, you receive the certificate. You take the exam at a Volkshochschule, a language school, or an official test center.
كيف تبدو؟
Depending on the test, the certificate may look different. On page 2, you can find an example of the "Deutschtest für Zuwanderer" certificate.