The phrase "activities of the party" refers to the things or actions that the party is doing or engaged in. It could include dancing, eating food, playing games, and socializing with others. Full definition
His role in the party's success, which involved journalistic contributions and involvement in other activities of the party between 1993 and 2000, is considered significant. (ghanapoliticsonline.com)
As can be expected, in this specific case the raised, clenched fist might evoke the Black Panthers, whose community social programs became a core activity of party members (even if one doesn't remember that to be the case). (miamiartexchange.com)