NSF develops public standards for food equipment and certifies products against them. NSF/ANSI 7 sets minimum food protection and sanitation requirements for the materials, design, construction and performance of commercial refrigerators and freezers, covering storage cabinets, prep units, display refrigerators, beverage coolers and ice cream cabinets, among others. Certified products carry the NSF mark.
In practice, the mark tells you the cabinet was designed to be cleanable and hygienic: food-contact materials are suitable, corners and joints are easy to clean, and the unit can hold food at safe temperatures under defined test conditions. NSF certification is not an Indian legal requirement, but some international hotel chains, QSR brands and their franchisees in India specify it in their equipment standards.
An international burger brand opening outlets in India might ask its local franchisee to buy prep tables and reach-ins that meet its global equipment standard, which may include NSF certification, even though Indian regulations do not require it.