The green pads are the vegetable, in Spanish Nopales.
The round reddish balls are the fruit, in Spanish Tuna.
Both are edible but if you are doing your own harvesting, you will want to be careful.
There are some very visible long spines but there also are tiny, invisible glochids that are far more irritating and difficult to remove from the skin.
This plant is growing at the edge of the road in my neighborhood and I have no intention of getting any closer to it.