Expressions Page
Applies to: 
SQL Server
SSIS Integration Runtime in Azure Data Factory
Use the Expressions page to edit property expressions and to access the Property Expressions Editor and Property Expression Builder dialog boxes.
Property expressions update the values of properties when the package is run. Property expressions can be used with the properties of packages, tasks, containers, connection managers, as well as some data flow components. The expressions are evaluated and their results are used instead of the values to which you set the properties when you configured the package and package objects. The expressions can include variables and the functions and operators that the expression language provides. For example, you can generate the subject line for the Send Mail task by concatenating the value of a variable that contains the string "Weather forecast for " and the return results of the GETDATE() function to make the string "Weather forecast for 4/5/2006".
To learn more about writing expressions and using property expressions, see Integration Services (SSIS) Expressions and Use Property Expressions in Packages.
Options
Expressions (...)
Click the ellipsis to open the Property Expressions Editor dialog box. For more information, see Property Expressions Editor.
<property name>
Click the ellipsis to open the Expression Builder dialog box. For more information, see Expression Builder.
See Also
Integration Services (SSIS) Variables
System Variables
Integration Services (SSIS) Expressions