Standard BW defination

Info area in BI is  similar to folders in a system.Info area   in general contains all objects used to evaluate for a business logical process

 Info Object :-it is the smallest information containing unit which can be (Key Figures, Characteristics). 

Key Figures : Data part of an InfoObject. They are quantifiable values. (Eg. Quantity Sold, Revenue)
Characteristics : Objects that are used to calculate and present Key Figures. (Eg. Sales Office, Customer)

Data source:- Data  source is used as a connector between Source and the Target.It contains Communication Structure, Transfer Rules/Transfer Structure. 

Application Component

:-Application Components are used to organize Data Sources

Infopackages.:- which load data from source to PSA table

Data transfer process[DTP]:- Load data from PSA to Data Target  

PSA

Persistent Staging Area is a data staging area in BW. It allows us to check data in an intermediate location, before the data are sent to its destinations in BW.
The PSA stores data in its original source system format. In this way, it gives us a chance to examine / analyse the data before we process them to further destinations. Most probably it is a temporary storage area, based on the client data specifications and settings.

Infocube:An InfoCube is a quantity of relational tables arranged according to the star schema: A large fact table in the middle surrounded by several dimension tables.The central objects upon which reports and analyses in BW are based, are called InfoCube