I needed this in an ELI5 too. Here's how AI broke it down:

Imagine you borrow a toy from a friend (the broker) to play with, but they want to make sure you don’t break it. To feel safe, they ask you to give them some of your favorite toys to hold onto, just in case. If the borrowed toy is really expensive (like a rare collectible), they might ask for more toys to make sure they’re covered if something bad happens.

In this case, the borrowed toy is MicroStrategy stock, and it's connected to Bitcoin (a very unpredictable and risky toy). The broker, Interactive Brokers, is now saying, "We’re worried something might happen to this toy, so we need you to give us even more toys (money) to keep it safe."

If you don’t have enough toys to give, they might take the toy back (sell the stock) to make sure they don’t lose anything. This change happens gradually, so you have a few days to figure it out. They’re just being extra careful!