I refund a purchases and after I submit they reply, your purchases is not eligible for refund, I don’t understand what is eligible ?

This is primarily a user-to-user support forum; other Apple users like you. You may want to contact Apple Support (there is a Get Support link at the top right of this page) or see the following from Request a refund for apps or content that you bought from Apple - Apple Support

Refund eligibility might vary by country or region. See the Apple Media Services Terms and Conditions for details. In countries and regions with consumer law protections, users retain their rights under these protections. In Australia and New Zealand, consumers retain their rights under the applicable consumer protection laws and regulations.