Terms one would be hearing when you are with Essbase

Hierarchy

Dimension

Members

Attribute

Dense

Sparse

PAG 

INDEX

Blocks

Cells

Calculation  Scripts

and the list goes....................

Dont Worry if you are newbie, i believe i can explain you in a better way for you to understand.

Hierarchy is nothing but a structural model of your organization in terms of its financial accounts,entities,products etc....

Dimension is nothing but criteria/measure upon which you can analyze your data. Ex: Accounts,Entity,Scenario,Version,Product,Year,Period etc..

Entity is nothing but any legal business unit ( may be in a different region or same ).