Imagine an empty room.
There is nothing in the room except for empty space.
Nothing but empty space?
Let's add a few things; maybe a table, another chair, a book shelf, a computer or two, a music player, a kettle and coffee set, some picture frames, a hundred books, memorabilia from our travels, a few cabinets to store our things and we add and add and add.
Now we have a room with a lot of stuff and very little space.
We all have such a "room", and as we were growing up, we'd been filling it with stuff. So much stuff that we'd forgotten about the space, but space, is what gives a room its function.
A room full of stuff is no longer a functional room, and a mind full of stuff is no longer a functional mind.
The practice of meditation is simply a clean-up of our very full and messy minds. The most utilised things will remain and are utilised more effectively. The clutter items are discarded and new space is created. The value of space or emptiness becomes obvious. The space has always been there, meditation is just a shift of focus, from contents to space. It's the process of finding awareness and staying in awareness. Like in clean-ups, when meditating, we are not adding anything, but rather, a process of letting go. It's not an easy task because we'd spent our lives accumulating the stuff. It'll take time, but a little by a little, we will find the right balance between space and content.