Is understanding a practice? Enlightened people doesn't have any desire, because they see impermanence in everything. All the things are useless to them. To achieve enlightenment , one required to practise deattachment, uncertainty through out the samsara. So , Is understanding a practise ?


If it is: We loose skills when we don't do somethings for long time. But enlightenment can not be undone.
If it isn't: When we do vipassana meditation for a long time, we started to see impermanance in every day life. We loose attachments to lot of things . What is happening there ?


I'm not sure I express and structured the question as I want . So Improves are well come.
OP: So , Is understanding a practise ?


Understanding arises through the practice.


  OP: If it is: We loose skills when we don't do somethings for long time. But enlightenment can not be undone.


Yes. As enlightenment is understanding of reality as it is and this does not change in light of new experiances.


  OP: If it isn't: When we do vipassana meditation for a long time, we started to see impermanance in every day life. We loose attachments to lot of things . What is happening there ?


Attachment leads to pain. When you understand this through Vipassana you do not get attached.