How to compose the following scene so that it doesn't look "empty"?

If you think the scene looks empty, I don’t think there’s much you can do to recompose the scene to make it look less empty whilst maintaining the original point. If the point was the line of trees, then you could play with the focus point (focusing on a closer tree would have put less emphasis on the bench), but doing much beyond that, in my mind is changing the scene.

If you don’t want it to look empty, change the scene. You could take a tricycle with you. You could take some bird / animal food and scatter it on the floor in front of you to attract some wildlife to the scene (have no idea how practical this is where you are). You could cut down what’s visible in the image, focus on the bench, a smaller number of trees, the poles between the trees... Or, you could embrace the emptiness and make that the focus of the scene. An empty bench by the trees, a discarded book, glove, hat, broken umbrella, newspaper, letter...

You seem to be listening to people on 1x telling you that you need 3 things to tell a story... Great, I’ve heard similar things about 5 and odd numbers in general. But fundamentally if you’re trying to tell a story you need to know what the story is. If you know that, then you’re far more likely to figure out what it is that is missing from the shot. A line of trees can make an attractive picture, but it’s not a story. The rigid restrictions placed on nature so that it can exist in built up areas might be the start of a story... but then you’d be looking for something to emphasise that order, such as more of the straight lines from the block of flats in the distance... or contrast it with the chaotic pile of pipes behind the trees.

If you want to tell a story, the first thing to do is decide what story you want to tell... and it may be that it needs several pictures to tell it... Personally, I don’t see anything wrong with empty as long as it’s there for a reason...