Short answer: The government agency that manages First Home Grants and Loans. Formerly Housing New Zealand.
Kainga Ora is the government agency that runs the First Home Grant and First Home Loan programs. They used to be called Housing New Zealand. They also build public housing. For first home buyers, they are the people who approve or decline your grant and loan applications.
Old Name: Housing New Zealand
New Name: Kainga Ora
Manages: First Home Grants, First Home Loans, public housing
Website: kaingaora.govt.nz