Transfer value of one column to another column into a new column based on condition
This can be solved using a number of methods. One of the method is:

df['new_col']=df['Bezeichnung'][df['Artikelgruppe']==0]


This would result in a new column with the values of column Bezeichnung where values of column Artikelgruppe are 0 and the other values will be NaN. The NaN values could be easily replaced at any time of point.

+-------------+---------------+---------+   
| Bezeichnung | Artikelgruppe | new_col |
+-------------+---------------+---------+
|     A       |       1       |    NaN  |
|     B       |       2       |    NaN  |
|     C       |       0       |     C   |
|     D       |       4       |    Nan  |
+-------------+---------------+---------+