Hi Vikram
BODS is an ETL tool in which we can extract data from any SAP or non SAP system.
To import an csv file in to HANA, we can use two ways as direct extraction of data or through writing queries. In the former approach we can use the "File" --> Import --> SAP HANA content --> Data from Local file". This process is used only if the file is present in your local machine. In the later approach you can use the query statement as "Import from" to import the file present in your BO server.
In the second approach the tables has to be created manually with the respective fields and their data types mentioned along with it. The repective data for the tables can be embedded in to the schema by writing the queries as "Import from..".
SLT is an alternate approach for extraction of data from the SAP system, and is best suited for the real time services while the BODS is used for the batch jobs since we deal with the scheduling and monitoring of jobs in it. All the transformation techniques and the DI platform techniques can be used to extract the data from the legacy system.
Best,
Sanjay