Yes. On the last step of the getting-started guide, choose Explore with demo data: a fictional company with its clients, opportunities, meetings and messages fills your workspace, so you can see My day, the Inbox and revenue in action.
To remove it: Settings → General → Demo data → Remove demo data. Only the demo records go (and the notes you added to them); your own contacts and deals stay in place. The same card lets you load the demo again later.
Loading and removing demo data is reserved for workspace owners and admins.