Is the work of a brother in a printing and photography shop permissible, given that he photographs and prints customers' files, including textbooks and notes, knowing that many of them may be protected by copyright? And is it permissible for him to photograph materials whose content he does not know, such as printed materials in foreign languages ​​that he does not understand?

Copyrights are protected and may not be infringed upon. Therefore, copyrighted material may not be photocopied, as this constitutes an infringement of those rights. The reference for knowing this is custom and contextual indicators. If it is not highly probable that the material is copyrighted, then there is no objection to photocopying it. Similarly, if it is not highly probable that it contains anything objectionable, then there is no objection.