Source Column Dependencies : When editing a mapping, you can view source column dependencies for a target column. Viewing source column dependencies lets you see from which source columns a target column receives data. To view column dependencies, right-click a target column in a mapping and choose Show Field Dependencies:
Here you can see CUST_NAME is dependent on both LAST_NAME, FIRST_NAME column from the Customer source table.
Object Dependencies : You may need to find out the dependent objects for any chosen object. Right click on any object to invoke the Dependency dialog box shown below.