That shouldn’t be too difficult.
Imagine if you have a layout for an activity that has a RelativeLayout that contains a TextView and an ImageView. Naturally one would think that the logic implementation of that TextView and ImageView would resides in the activity (or it’s view model).
However if you make a customer view (that has the RelativeLayout that contains a TextView and an ImageView), then all the logic now would reside within the custom view, instead of the activity.
That’s a separation of concern.