When do toddlers begin to retain information?

My daughter is nearly 3, and honestly it’s like speaking to a brick wall. Toddlers do things for a certain type of reaction, so try changing your reaction or removing the item they are pouring with perhaps? Repetition is boring for us adults, but children need it. So just keep doing what you’re doing.

When looking at different aspects of learning they all develop at different rates, however when it comes to being a toddler, they all seem to act the same way🤦‍♀️🤣. My little is bright enough to follow instructions with many steps, however he’ll still ignore and defy me when it suits and has his own ‘toddler terms’🤣

They all develop different things at different times.
Our daughter follows instructions well (for the most part) and remembers what we’ve told her. On the other hand, she isn’t writing numbers (using your example here).
They will develop different things at different stages and don’t tend to be good at everything at once as they focus on different skills

I suggest redirect, if he wants to keep pouring perhaps he can bring a doll or action figure into the tub and he can pour over the doll instead? And have fun with him too! So when he pours the water on the doll instead of the baby show how happy u r about that and for the Dyson does it actually vacuum? I mean cuznif it does put that kid to work and give him a section to focus on, and if it vacuums maybe u can sacrifice a little section of ur floor and add some heavy crumbs so he can see that he needs vacuum what's dirty and not what's already clean? And if this doesn't work thn u have to set limits as someone mentioned above take the pouring toys away and stick to it. "We are having a hard time keeping the water off our brother, let's play with something else, pouring is finished."