Jambo! is a node of Mastodon, a decentralized, open source social network. It is just one part of the network, run by Walialu . It is not focused on any particular niche interest. Jambo! (jam-buh!) is a Swahili greeting or salutation with an exclamation mark. It is similar in meaning to the English word Hello!.
Mastodon is a social network based on open web protocols and free, open-source software. It is decentralized like e-mail.