Hello pls what is hepatitis B, and what is d cause and the treatment? And is it a chronic disease?

It is a virus. That is often spread through sexually contact or blood transfusions(less common in this day and age). It mostly effects the liver. For some people it only cause short term issues when they are exposed(acute hepatitis B) but 15-30% of people with acute hepatitis B will develop a long term chronic hepatitis B. There is much more to know but it's too complicated for this small space.