The Usage tab is a read-only dashboard of your storage consumption. Usage is sampled automatically about once per hour, so new activity can take up to an hour to appear.
Two cards at the top show your current disk usage and your bucket quota.
If your plan has a quota, a progress bar shows how full the bucket is:
When the bucket passes ~80% full, an upgrade card appears offering to increase your quota through the service's configurable options — the change applies immediately after checkout.
Two cards summarize the current month and the previous month:
"No usage snapshot yet" simply means no sample has been collected for that month yet.
See Billing, Overage & Cancellation for how the estimated amounts translate into invoice charges.