Q.1) What are SAP reports?
Ans: SAP Reports are event-driven programs using ABAP/4 programming langugage. These reports are used to fetch business-specific data from SAP standard databases under specified selection criteria, fetched data is processed to display result on output screen. User develop SAP report object on ABAP editor using the standard SAP transaction SE38.
Q.2)What are [...]

If i_final is the final internal table containing  retrieved business data, and w_final is the work area of your final internal table, then you can display the result (classical report view) by writing code in following manner.
*&———————————————————————*
*&      Form  TOP_OF_PAGE
*&———————————————————————*
*       For data display
*———————————————————————-*
form TOP_OF_PAGE .
IF NOT i_final[] IS INITIAL.
ULINE.
WRITE:/1 sy-vline,
2 ‘PO Number’,
12 sy-vline,
13 ‘PO Line Item’,
25 sy-vline,
26 [...]

In SAP, highest level of organization structure is client.Whenever we login to SAP system, we login to a specific client. Data in the R/3 sytem is categorized as client-dependent and client-independent.
Client dependent table:
Client dependent tables are always client-specific. These cannot be accessed from any other client. First column of any client-dependent table is always client(type [...]