Okay, so imagine you're building with LEGOs. You have a bunch of different pieces with different shapes and colors. When you put them together in certain ways, they can create different things.
Syntax is like the rules for how you can put the LEGOs together. It tells you which pieces you can use, where you can put them, and how to connect them. Just like how in English, you need to put words in a certain order to make a sentence.
But just putting LEGO pieces together in a certain way doesn't necessarily mean you've built something that makes sense. For example, if you made a tower with a chicken on top, that wouldn't really make sense.
So semantics is like the meaning behind what you're building. It's what makes sure that what you've built makes sense and has a purpose. So maybe you build a spaceship out of LEGOs. The syntax tells you how to build it, but the semantics tells you what it means and what it can do.
The syntax-semantics interface is where the rules for building things (syntax) and the meaning behind them (semantics) meet. It's like where the LEGOs you put together create something that actually makes sense and has a purpose. Just like in language, where the order of words (syntax) creates sentences that have meaning (semantics).