Verstehen Sie? is not equal to Do you understand?
While it is completely acceptable and quite common for Germans to ask “Verstehen Sie?”, English speakers will find it impolite when somebody asks them “Do you understand”. The English translation might be taken as an insult because it questions the person’s ability to understand. These are suggested alternatives to “Do you understand”:
Is everything clear? Is it clear?
Did I explain everything well?
Does it make sense?