SAP HANA is SAP own database, which replaces old licensed databases, for example replacing oracle database. SAP HANA is not only a database it is more than a data base. With SAP HANA SAP introduced data reduction by making less tables in data and making all of the server processing in-memory.
With SAP HANA there are many new features and functions are introduced: there is new UX design apps and apps also are introduced. In past SAP recommended making separate database server for APO and BI that cases lot of data syncing issues, but with SAP HANA it seems SAP simplifying there databases to single database for almost off of the applications.
SAP Functions are not very much effected by SAP HANA for functional consultant or user. SAP HANA made reports very much faster but not all of the companies have adopted the SAP HANA.
SAP HANA have to be built on top of the open source Linux system. It is about time all of the new innovating technology is coming from open source. SAP HANA installed on suse linux.