This is the 8965th most frequent Russian word.
разобраться
To figure out, understand, or sort out.
In this sentence, 'разобраться' is used reflexively to mean 'to figure out' or 'to understand' a problem or situation.
Мне нужно разобраться в этой задаче.
I need to figure out this task.
Here, 'разобрались' indicates successfully understanding and resolving the aspects or details of something collaboratively.
Мы разобрались во всех деталях проекта.
We understood all the details of the project.
In this example, 'разобраться с' means addressing or sorting out a particular issue or set of materials.