Friendship. Linguist David Eddyshaw (Languagehat blog) explains Dagbani zɔsimdi as 'friendship', the first part of the title Zosimli Naa. The Dagbani Dictionary does not list zɔsimdi as a headword but glosses zo and simdi as 'friendship' and zɔsimo as 'friend; friendship'.
The visit was meant to strengthen zosimdi, the friendship between the two communities.