questions for activity log

Hi,

I read the document  Track user activities in Power BI - Power BI | Microsoft Docs, but I still have many questions for the activities in log. I wonder if you can help me clarify what the activity might really means. For example, I'd like to know what button I need to click so the activity log will show "GetRefreshablesAsAdmin." Thank you!

The Activities I have questions with:

1. GetRefreshablesAsAdmin 

2. GenerateCustomVisualAADAccessToken

3. GetSnapshots 

4. InsertSnapshot

P.S. I tried to search what a snapshot really is in Power BI, and in what time the snapshot will be generated? I cannot find the answers... Does anyone know the answer? Thank you.

V