Here is a sentence from a schedule planner app:
In the app, you can easily group to-dos into projects and drag tasks within and between them.
I am not sure if the word "them" is used here for "to-dos" or "projects."
I would assume them refers to projects, because to-dos and tasks are pretty much synonymous. But the language here is somewhat confusing and ambiguous, as you can tell. Maybe it would be better understood if written this way:
In the app, you can easily group to-dos into projects and drag them within and between projects.