Whenever you're entering your work hours (both in Slack and in nikabot.com), you'll be shown the list of projects that are available for you to select from.
However, the best way to see and manage your team's projects is to visit the All Projects page under the Manage section in your team's console. You'll see the list of all existing projects, including archived ones, total number of hours logged and latest activity.
This page is always available to admins. Non-admins may see it if they've been given the right permissions in the Team Settings page.
On Slack, you can also type the command
list projects when talking to Nikabot and she'll show you the list. If you're looking for a specific project, you can add a part of the name and Nikabot will find project names that include it in the name (e.g.:
list projects foo).