Sorry medyong baluktot pa Tagalog ko. My friend explained it like this for less techy users:

• Lemmy the platform is planet Earth
• “instances” like lemmy.ml, lemmy.world, beehaw.org, etc. are like the different countries on Earth
• When someone signs up, the user picks one instance to be a part of, like how an Earthling becomes a citizen of a country
• If you register at lemmy.ml, that means your *home instance */ “home country” is lemmy.ml, but you can “travel” to lemmy.world, another instance / “country”, to check out and subscribe to their community
• When you subscribe to a different instance that’s not your home instance, you can still participate in their content, and other people will be able to see which instance / “country” you’re from
• Each instance can have its own version of the same “subreddit”, so you can have a c/Philippines in your home instance that is different from a c/Philippines in another instance. But you can subscribe to both separately (sidenote: c/<name> is the naming convention used here I think)

Someone please correct any of this if any of it is wrong, I’ll happily edit