You can set the opacity of any graphical object such as image, video, picture, and text! This can be especially useful, for example, if you want to layer another object, such as text, on top of a more opaque object.
To set an object's opacity, first of all select the object from the Timeline or on the Stage. Then, under the 'Object Properties' on the right hand side of the Stage, you can see the Opacity slider:
Just drag the slider according your requirements, and this will change the opacity of the object as in the example with an apple below: