You can view the list of communities you are a part of in this view. You can click the in the right top corner of the API Portal window and click Communities to navigate to this view. You can manage the communities if you are a Portal Administrator or if you are a community administrator. As a Portal Administrator you can create a new community, add members to a community, define a community administrator, add or remove APIs from a community, add or remove user groups from a community, and so on.