Okay kiddo, have you ever ridden a bike? You know how there's a chain that connects the pedals to the back wheel so you can ride the bike? Well, sometimes these chains can get really dry and rusty, and that makes it hard for the bike to move smoothly.
But some chains are special - they're called self-lubricating chains. That means they have special stuff inside them that helps them stay slippery and smooth, even if you don't put any oil on them.
The special stuff is called a lubricant, and it's kind of like a very slippery liquid. But instead of being loose and watery, it's trapped inside tiny capsules that are built into the chain.
When the chain moves, it squishes the capsules and releases the lubricant. The lubricant spreads all over the moving parts of the chain, making it easier for everything to slide around smoothly.
So basically, a self-lubricating chain is a bike chain that comes with its own oil built right in. That way, you don't have to worry about putting oil on it all the time to keep it working correctly. Pretty cool, huh?