Welcome to the Wefugees Community and thank you for your question.
If someone gets deported, the German authorities most probably impose a re-entry ban (ban on entry and residence) for Germany and the Schengen area for a certain period (in most of the times for five years, if I am not mistaken). According to Section 11 (4) of the German Residence Act there might be a possibility to lift or at least shorten the re-entry ban. To have a chance to apply successfully, the person should have paid the costs of the deportation. People need to present their reasons for lifting/shortening of the re-entry ban to the BAMF, which will decide on this. As the procedure is quite complicated and difficult, I would strongly recommend to get support by a good lawyer (specialized in residence/migration law) in this case.
I will also link two of our experts here: Dear @mbeon-Rukundo or @mbeon-fardeen: Do you agree with my explanations and is there anything you would like to add?
However, also don't hesitate to get back to us with any further questions.
All the best,