The beetroot is a food item and can be cooked. They have a chance to spawn in barrels and can be grown in cropplots. The beetroot can be eaten cooked or raw however if it is cooked it will restore a bit of thirst too.
How to obtain
If you haven't got them yet simply find them in a barrel. You can grow them for an extra beets (you can do this with potatoes to)
The beet is a red color and has a stump coming out of it but once cooked it gains scratches on it and a more charred color going from purple-ish red to redish black