Change Visa of Language learning to working Visa

Hello @nizartaktak , thank you for your question on our platform. As I understood you are currently in Germany already and have come here on a visa according to 16b Abs 5 AufenthG, which is a visa to start your studies in Germany. . 
Now, you would like to change this residency to a working permit, since you received a job offer. Whether or not you can do this, depends on the job offer you received and your qualifications. 
I would recommend seeking support for a change of residency with a migration counselling center before seeking out a lawyer. They will be able to help you navigate the next steps. . You can search for a youth migration center if you are under 27 here: https://www.jugendmigrationsdienste.de 
 Or if you are older than 27 you can search the BAMF Navi: https://bamf-navi.bamf.de/en/Themen/Migrationsberatung/ 
 If you need help in searching for an advise center, please let me know. 

If you are still abroad then you can apply for a work visa if you meet the requirements. You can find the requirements for a skilled work visa here: https://handbookgermany.de/en/visa-skilled-workers 
I would also recommend you connect the number from „Make it in Germany“ they can also give you advise if you are still abroad. You can find different ways to contact them here: https://www.make-it-in-germany.com/en/service/contact-us/hotline 

 Please let me know if you have any further questions. 
 Best wishes