Shuldn't here be Apakah instead of Apa? Apakah is used for yes/no questions and this is such a type of question.
Apa and apakah are the same. Although, apakah is more formal than apa. The suffix –kah is used to turn regular question sentence into a more polite form.
What is the role of bisa in this sentence? i understand what it means but how does the sentence change without it?
Apa(kah) kamu bisa makan sendiri = Can you eat by yourself?
Apa(kah) kamu makan sendiri = Do you eat by yourself?
Not a native speaker, but this is what I understand.