In short, information.
G.I Joe man. "Knowing is half the battle!"
But really, information. Knowing an enemy is in your jungle or even their jungle alone is valuable information. Can we collapse and kill them to set them back? Who is on their way to try and save them? Spot a tp coming in? All useful information to plan with.
Warding Baron/Drake (and/or around pit). This one can be two fold, but breaks down to 1. Prevention of enemy team getting it.
Anyone have a global ult they can use to maybe steal it with good timing? Can your team get there to to maybe pull/scare them off? To steal it?
Can your team quickly burn it before an enemy gets there? Is it barely done and the enemy collapsing on you? Time to bail then maybe. Even a support can steal a Drake or Baron if the enemy doesn't know you are there.
Enemy lane missing? A ward has spotted them approaching your lane. Consider backing off, or bait if jg and whatever lane is missing is collapsing on them.
All this information comes from vision and vision denial.