Actually, doing this pretty easy there's a css property called
backdrop-filter this property add a graphical effect to background and you can add many things to background one of them is a blur effect.
So, to apply a backdrop blur filter first you have to choose a perfect color for background you can even add a image it will make it blur, but to make the see-through glass part work we have to make the color transparent.
I use VS Code todo stuff so it gives a color picker option
The color I used is a translucent white
#ffffff3f , I tried to find an online color picker and fund this RGB COLOR PICKER , you can use this to get a transparent color.
so after setting up background no use put
backdrop-filter:blur(5px); add the blur radius as much you want and this will add a frost glass effect to your div.
backdrop-filter: drop-shadow(4px 4px 10px blue);
Try these too.
Source: MDN Web Docs