What does obliteration of right costophrenic angle indicate?

This means there is something that is taking up this space. The costophrenic angle is typically clear so if it is not clear, there could be fluid in this space or some other abnormality. There could be an infiltrate, like a pneumonia, nearby that is causing the space not to be clear on an imaging study. Much of the time, it represents a fluid collection which needs to be diagnosed.