This is "Bug 1," who has an identical look-alike on another leaf.
This is Bug 2, who is shorter rounder than Bug 1, but with the same colouring.
This is Bug 1 from another angle.
I think they are some variety of damsel bugs.They move fairly quickly when startled, which suggests to me that they are probably predatory. They're hanging out on the broad beans, and broad beans are often plagued by aphids, which damsel bugs apparently love. I haven't seen much evidence of aphid damage on my plants, but perhaps that's because these guys and their friends are scarfing them down before they can ruin my lovely beans.
I didn't take biology in high school, so everything I know about living organisms has come from gardening. Once upon a time, I wouldn't have paid much attention to three little green bugs, but now that I have plants to protect, I want to know all about every crawly and/or winged thing that passes through the yard. Friend, or foe? Predator, or prey? Fan of succulent green vegetables? Keep moving. Fan of slimy slugs or of tiny sap-sucking aphids? Pull up a chair and stay a while!