This is the picture I have took while the solar eclipse. What are the objects that are like a crescent and blue sphere? I know that such (rays) appear whenever we photograph the Sun but what is the reason for it to be specifically a crescent?
Those are due to lens flare. This usually happens when the object you're taking a picture of is very bright. These happen when a light source follows a pathway through the lens that contains one or more reflections from the lens surface. The lens is made up of glass. When light is incident on the glass (lens), sometimes, instead of refracting and going through, the light is reflected back towards the sensor or the film. This is registered as a lens flare.
The shape of the lens flare depends on how the light is reflected off the lens and the shape of the source. Eclipse-shaped lens flare occurs as the shape of the source (here, the sun) is shaped like that (that's because you took the picture of the sun during the solar eclipse).