[Anteino]

pawn Код:

new language;

public OnPlayerConnect(playerid){
    return ShowPlayerDialog(playerid, 1337, 0, "Language", "Please choose your language", "Croatian", "English");
}

public OnDialogResponse(playerid, dialogid, response, listitem, inputtext[]){
    if(dialogid == 1337){
        language = response;
        return 0;
    }
    return 0;
}

/*
    then wen you send a SendClientMessage you do:
    if(language == 0) SendClientMessage(playerid, COLOR_KRED, "Niste autorizirani za koristenje ove koamnde");
    else SendClientMessage(playerid, COLOR_KRED, "Whatever that text above here meant :)");
*/

I think that is what you need.