Okra, gumbo or ladies' fingers is related to mallow and produces edible green seed pods. It originated in Africa and is now cultivated in many tropical, subtropical and warm temperate regions.
When cooked the pods produce slime. If you do not like this you can reduce it by cooking the okra very quickly, such as in stir-frying, or mixing it with something acidic such as lemon, tomatoes or vinegar. In gumbo, a classic stew using okra, the pods are thinly sliced and then cooked for a long time and then the slime dissolves. Of course, some people like the sliminess. Immature okra pods can be pickled and I think the leaves can be used as a thickener.