How I can make a checkbox filter?

I need to find a solution for my script, because I gives me duplicated results.

There is something that I made:

https://jsfiddle.net/4m3twsjd/1/

        function myFunction() {
        if(a % 2 == 0){
          document.getElementById('h1').innerHTML += M
        }

        else {
          document.getElementById('h1').innerHTML = document.getElementById('h1').innerHTML.replace(M, '')
        }
        a++
}

How to make it to not show the same element when clicked two or three checkboxes ?

Also how make visible something like this (photo means included picture): Photo | Name | Description | Link

Thanks you in advance all for this. I need some simply code, because I'm not a coder.