Hello Sebastian,
data access from an UI5 application should be done by an OData service. How you can define an OData service on HANA for an e.g. table is described at Data Access with OData in SAP HANA XS - SAP HANA Developer Guide for SAP HANA Studio - SAP Library (read the sub chapters).
To consume an OData service in UI5 you can use the UI5 ODataModel (sap.ui.model.odata.ODataModel or sap.ui.model.odata.v2.ODataModel if you have a newer UI5 version).
A simple demo for a table is described in the UI5 Explored app: SAPUI5 Explored
The demo uses a JSONModel, but you just have to replace the JSONModel by your ODataModel + adjust the column and binding information in the XML view to your needs. This is a very simple example where the Model is created in the onInit method of the controller. If you wanna implement a UI5 app according to the standards I would recommend to check the UI5 developer guide (SAPUI5 SDK - Demo Kit).
Regards,
Florian