Additional contact-related features and issues within Microsoft Teams Free
The "People" tab is not yet available in Teams Free application (personal account), but should be made available soon. This feature is currently only available for users with business account.
However, if you wish this feature to be available sooner, then you might join the Teams Insider program. This will enable the People tab.
https://teamsinsider-dev.azurewebsites.net/blog/people-app-in-teams-free/
When this feature will be made available for you, pressing the People icon will open a list of all your personal contacts, incl. contacts with whom you have only chatted previously on Skype (if you have previously used Skype).