The income slab of ₹0-4L is called the basic exemption limit (BEL). In case of NRIs, they do not get the benefit of BEL against their capital gains income. So your capital gains will be taxed as per the applicable rates.
However, if you have other income sources such as rent from Indian property or interest income, you would not have to pay any tax upto ₹4 lakh for such normal slab rate income. (Capital gains income are also called special rate incomes).
Hope this helps