What is SAP Fiori ?
SAP Fiori is the (re)new applications for the Business Suite and completely build in SAPUI5. It uses OData to communicate with the SAP Business Suite and for this you need to install a SAP NetWeaver Gateway and UI Addon for NetWeaver plugins into your SAP landscape, if you are not already on the SAP NetWeaver 7.4 stack. At this moment SAP delivers 65 Fiori application and this will grow to 200 Fiori application in 2014. As a developer you will need beside ABAP knowledge also knowledge of SAPUI5, HTML5, jQuery and OData.