All objects are arranged as stacks in the InDesign workspace. Every object has a X, Y, and Z coordinate which will pinpoint the location and orientation of the object with respect to the rest of the stack. You can bring the objects forward or move them backward as needed.
To do this, select the object that you want to move forward or backward, go to the Object menu, then to the Arrange submenu and select the appropriate option.
Note that sometimes, the object might appear as though it has disappeared when you bring it to the front or back. It has not gone anywhere. There could be another object layer in between which is causing the object to visually disappear.
For example, the car in this image, ‘disappears’ when sent to back but comes back when brought forward. This is because of the presence of another layer between the car image and the text object.