Communication of proposed adjustment u/s 143(1)(a) of Income Tax for FY 2018-19 (AY 2019-20)

What is the notice for

But 143(1)(a) is intimation of assessment as income tax authority has reassessed your total income and made adjustments relating to your income and if any tax payable or refund granted such amount will be paid by you or Credited to you but if any pending order has been ordered then you have to rectify such return online on income tax portal

Can I submit it after delay of one year