That will be your cluster cost per month, that includes, HW, Software and the Level of support selected.
To directly answer you question if you set up a cluster and it is 0.0225 / hr and you never use it you will still be charges for that cluster, there is not concept of idle / standby etc. Once you provision it you will be charged hourly, if you destroy it, the charges will be rounded up to that nearest hour and stop.
There are Data Transfer and Storage cost, as with most cloud services.
- Ingress (Inbound) is Free.
- Egress (Outbound) has a Cost as well as Interzone
- Plus there are Snapshot Storage Costs
Long story short Typically the costs are ~10%-20% of your monthly.
You can read about that here
You can read about how to view those cost here