Could anyone explain this reinforcement details?

That seems like a pretty typical reinforce concrete slab detailing to me. What specifically do you need help with? Is this output from one of the Bentley products?

Hi Nasir,

I think this kind of slab detailing is produced by STAAD Advanced Concrete Design (SACD). My suggestion here is that you should read this sectional reinforcement detail in conjunction with Top and Bottom Reinforcement Plans.