To examine a user's activity for the time of using the business account, you can view their log. To do so, open the Users section of your business account, locate the user you need to view the log of, and click the log icon, located between the green and red button to the rightmost of the user. This log will provide you with information about the user's activity, for example: devices, through which the business account has been used, uploaded folders, shared files and folders, etc. You can also sort the log items by date “from-to”.
Also, there is an entire section of your business account, called Logs. It lists all logs of all of your users. You can filter these logs by users, teams and date.
Note that only business account owners and users who hold View Activity Logs permissions can view users' logs.