There are many guides out there where people show usable architectures or worship one architecture as THE STANDARD, writing whole Books about old Methods applied to modern problems. In difference to these, this is only a rough answer:
Android encourages you to use MVC or some MVC Variant (MVP/MVVM/...) for the Activities/Fragments.
You can apply the 3-Tier Architecture on the whole App.
Presentation Layer
The MVC or variant is applied to the Presentation Layer. Your Presenter/Controller handles your view, inflation and modification, ui control bindings like onclick events, maybe some effects that are bound to this view alone and so on.
Business Layer
Here is your business logic. Your workflows, processes, rules, ...
Data Layer
And data handling goes here.
The Others
It's a good start to keep things in these 3 Layers, for both maintainability and testing. This is the basic outline of my apps, both on Android or iOS but I'm not always pressing everything into these 3 Layers. For example Components for scanning Bluetooth devices, doing downloads in the Background (or other Background services and Tasks) or adding a Camera Preview with full set of controls. I keep those separate for reuse without the troubles of writing and importing a library.