How can I look at what is in my cloud?

Settings/iCloud/Storage/Manage Storage.

Manage your iCloud storage

You can also go to iCloud.com using a computer and see what is synced.

Some items, such as backups and Safari related sync, can't be seen.

Hi - iCloud is a collection of services. For example, iCloud Drive is one part where you store documents, etc. Here is more info that may help: iCloud - Official Apple Support