I can't edit the page for some reason, but Cacus Steven's dialogue here is... off. When Steven squabbles with the cactus, then places a box over it, it shouts at him: "Wide you say all that stuff? Wide?!" Steven grumbles back, "Oh, you know wide."
The point of this exchange is that it's garbled. It's the kind of fascination with words that this show always does, with the Cactus repeating "wide" in place of Steven's contraction "why'd," not understanding it as a contraction or exact usage and just parroting it as best it can, then Steven lightly mocking its bizarre usage by repeating it back verbatim.
You miss the whole punchline here, the reason why the exchange is funny: "Oh, you know wide."
This is a very Steven Universe kind of humor.