This is the 10975th most frequent Catalan word.
separar
To divide or set apart.
Here, 'separar' is used to mean 'to sort or divide something into different groups or categories'.
Vaig separar els llibres per categories.
I sorted the books by categories.
In this sentence, 'separar' indicates the action of keeping items apart because of their characteristics or treatment—often for practical reasons.
Hem de separar la roba blanca de la de colors abans de rentar-la.
We need to separate the white clothes from the colored ones before washing them.
Here, 'separar' expresses the action of ending a union or relationship, used metaphorically.