It is on contour similar to a swale.
It isn't a ditch that is made by digging down it is instead a mound that is piled up.
But I think you might be asking "what is it good for".
Is it good for >absolutely nothing".
It's a depression like a swale that lets water soak in, vs sheet off.
It is not like a raised bed/huglekulture, that I can plant annuals in., etc, etc
It can be a mini-windbreak
It can stop and trap the leaves and other things that are sheeting off the property in a rain.
It attract birds and collect deposits of fertility/manure.
It is a habitat for lots of critter.
You could harvest mushroom form it, if desired.
It slowly compost so, a super slow compost pile.
It makes your garden look artsy and clean, and soothing.
It could create quasi-terraces,if it traps enough erosion, and leave litter.
It can turn into a hedgerow.
It can be a wonderful border.
Iterations are fine, we don't have to be perfect
I didn't like the taste of tongue and it didn't like the taste of me. I will now try this tiny ad: