Hi vijaya biradar,
We can find information about the loop activity in the above documentation:
To further help please specify the use case.
A loop is used to execute repeated actions for a list of objects. For each iteration, the flow inside the loop is executed. The loop can be configured to iterate over a list or be based on a Boolean expression.
The object you're retrieving might be through association or directly through the database with any of the XPath constraints that would retrieve your list of objects for each time the value enters the loop as per the loop type you choose.
Loop Type :
While (Condition Is True)
So this is how loops are in Mendix to access the retrieved data.
For more info : Loop Guide
For more information let me know the use case to make a better understanding on the loops in mendix.