The Dashboard is the first page you see after signing in as a trainer. It shows how many labs you are responsible for.

At the top, Overview gives two totals across every lab type:
Below that, one pair of tiles for each lab type shows TOTAL LABS and ACTIVE LABS for that type. The types are Pre-Configured, Custom, Hypervised, Shared, Wise, Cloud, Manual and SaaS. For what each type is, see Lab types.
Select Running Labs in the sidebar to see and manage the labs themselves. See Running labs and trainee instances.