A very pretty effect and definitely easy to apply.
To begin, we simply assign the .bg-tex class to an element with text
To give the effect we simply give the bg-text a background-image with the url of the image we want to use as a mask.
After that we need to create the actual mask, so we give a background-clip: text;
As the last two steps we now give a color: transparent to the text and a background-repeat to not duplicate the image