class HomeScreen(Screen):

    def show_tasks(self):
        global user

        tasks = DB.get_tasks(user) # Returns an array of tuples
        for task in tasks:
            self.add_widget(Label(text=task[1]))

<HomeScreen>:
    name: 'home'
    FloatLayout:
        BoxLayout:
            orientation: "horizontal"
            pos_hint: {"x": 0, "y": 0}
            GridLayout:
                id: grid
                rows: 4
                cols: 1
                padding: 10
                spacing: 10
                row_force_default: True
                row_default_height: 40
                Label:
                    text: 'Your Tasks:'
                    size_hint_x: None
                    width: 200
                    font_size: 24