What does this icon mean?

This icon relates to Apple Continuity - a feature that allows your to continue a task started on one device (e.g., your Mac) on another (e.g., iPad).

The illustrated icon relates to Safari - and the badge indicates that Safari is open on your Mac computer. Tapping the icon will open the same web-page on your iPad as that currently being viewed on your Mac.

Use Continuity to work across Apple devices - Apple Support

That’s Safari, with a recent link made available from (handoff) another of your local devices.

Use Continuity to work across Apple devices - Apple Support

The compass app.