An "Arbeitsbuch" (Workbook) is a common component of language courses, providing exercises and activities to support learning.
"Netzwerk" is a popular German language course used in many language schools and universities around the world. B1.1 refers to a specific level within the course, corresponding to the B1 level of the Common European Framework of Reference for Languages (CEFR), which is an intermediate level. Netzwerk B1.1 Arbeitsbuch Pdf