Hi Meenu,
As Michael mentioned you can't export roles and users in a general way.
To add to it, you can always export users and roles if they are created used development workbench. That means if your developer has created any repository roles or users using development workbench or WebIDE you can export them by assigning those roles/privileges to a package/delivery unit. Make use of studio/HALM/CTS for that.
However to export users and roles created by admin workbench using gui can't be exported.
Happy HANA
**Deepak Chodha