If using canned red beans, drain and rinse them well. Drain the canned corn.
Dice the cucumbers and both bell peppers into small, even pieces. Finely dice the onion. Chop a little parsley. Mince the garlic.
Add cucumbers, peppers, onion, parsley, red beans, and corn to a large mixing bowl.
Add salt, black pepper, cumin, and paprika.
Pour in olive oil and lemon juice, then toss until evenly coated.
Taste and adjust seasoning (more lemon or a pinch more salt, if needed).
Chill 15–30 minutes if you have time, then serve.