How can I make this include a tag?

1. You need an "end"
2. Who is "Player"?
3. What is "newName"?
4. Why does it have an "and" when it there isn't even an if statement on line 2.

game.Players.PlayerAdded:connect(function(Player)
    if Player:IsInGroup(2535914) then
        newName.Name = "[LEGV][" .. Player:RoleInGroup(2535914) .. "] ".. Player.Name --What is "new name?"
    end
end)

Try this with a function:

function newName(StatName, char) --Edit this part.
    local billboard = Instance.new("BillboardGui", char)
    local name = Instance.new("TextLabel", billboard)
    name.BackgroundTransparency = 1
    billboard.Size = UDim2.new(0,1,0,1)
    name.Text = StatName
end

game.Players.PlayerAdded:connect(function(Player)
    if Player:IsInGroup(2535914) then
        Player.NameDisplayDistance = 0
        newName("[LEGV]["..Player:RoleInGroup(2535914).."]"..Player.Name, Player.Character)
    end
end)

Hope this helps. You had a lot of errors.