What is the Aliases pane in Sparrow?
No this is not a file alias (which is the same as a shortcut in windows) but an email alias. An email alias is an additional email address for an existing account.

You create an account with an address email@example.com and then a series of additional address for the very same account (the aliases).

You will have


one account
several addresses


It is the same principle as shortcuts and aliases for files but in another context.