SAP HANA is a database.
But it also contains an Application Server.
SAP HANA is not only for BI/BO guys as there are many other things.
Now we can use HANA for Web Development also and for that we use JSON, JavaScript, OData, JQuery and SAPUI5 along with HTML 5
Check this blog by Thomas Jung on XS Services that use Application Server:
You can find more information about HANA and Cloud Portal here :
http://scn.sap.com/community/hana-cloud-portal
There is no prerequisite to learn HANA and anyone can learn SAP HANA
According to me SAP Portal co-relates with SAP HANA through Cloud only.
For more info on HANA you can also check my blog :