title

[hoary mural]

billboardgui to display above their head, player:GetRoleInGroup(groupid) to display the role

[golden seal]

You will want to design a billboard GUI and place it in the player's head with the studs offset being something like Vector3.new(0,1.5,0)

when the player joins:

local Players = game:GetService("Players");

Players.PlayerAdded:Connect(function(player)
    local character = player.Character or player.CharacterAdded:Wait();

local billboardGui = Instance.new("BillboardGui", character:FindFirstChild("Head");
-- other billboard gui properties here, and atext label or something

if Player:IsInGroup(groupId) then
if player:GetRoleInGroup(groupId) == 255 then
    billboardGui:FindFirstChild("TextLabel").Text = player.Name .. " | " .. "Owner"
end
end
end)