Tiles display useful information, such as Popular Content or Featured People.
You can use a tile as is or customize it to display specific information. Different tiles are available by default in different places (spaces, groups, Your View, and so on). For example, the HR Pre-Hire Collaboration place template includes the Helpful Links and Action Items tiles by default. If you own the place, you can choose not to show these default tiles, and instead select different tiles.
Here's an example of the Top Participants and Upcoming Events tiles: 