From the homepage:
εxodus analyzes Android applications in order to list the embedded trackers.
A tracker is a piece of software meant to collect data about you or your usages. So, εxodus reports tell you what are the ingredients of the cake.
εxodus does not decompile applications, its analysis method is legal.
It should be noted this is not any sort of actual anti-malware tool. By “lists the trackers” it just means it looks for strings in the compiled bytecode. This is prone to false positives (if the “tracker” classes are stubbed out, e.g. in Fennec F-Droid) and doesn’t actually tell you if or how these libraries are actually used.