This is the 619th most frequent Serbian word.
активностима
"Активностима" means "activities" in English (dative/instrumental plural form).
In this sentence, 'активностима' is used in the instrumental plural form to indicate the means by which or the context within which the action occurs.
Учествујем у различитим активностима током викенда.
I participate in various activities during the weekend.
In this example, 'активностима' functions within the context of a prepositional phrase to indicate the circumstances or scenarios being addressed ('future activities').
Разговарали смо о могућностима учешћа у будућим активностима.
We discussed the possibilities of participation in future activities.
Here, 'активностима' is used to specify the setting or method ('group activities') in which the support is given.