Toddlers babble, but that doesn’t let their caretakers off the hook. When the kid tries to talk or learn, play along!
And I don’t mean “play” along – this is serious business for the little brats. Every additional match between a written word, a sound, an image, a real object helps construct the base on which they can bootstrap the rest of their knowledge.
So, when a little guy in your care comes over, points at something and says something unintelligible, please don’t patronize them with something like “that’s very nice, let’s go somewhere else”. Make your best guess as to what they may have been referring to, and start talking about it. If you are dealing with a smart kid and can cue in to his kinds of underdeveloped feedback, it need not be a frustrating process. Your efforts will make a difference.