Hi Fabio,
Really nice!
Here's what I know about the difference between "absolute" and "relative":
Relative means it's relative to the element's normal position (where it would be positioned based on the flow given by HTML), and you can move it with top/left/bottom/right.
Absolute means the position will be determined relative to the closest parent element.
In this case, the child element (the one you want to move) has to have position absolute, and (important) the parent element must be set to position relative.
In your case, the "quote" is a child of the parent "testimonial-1". You correctly set the parent "testimonial-1" to position: relative, and the child "quote" to position: absolute.
Hope this helps a bit. Please reach out if this is still not clear.
Corina
PS. If the parent is not set to position: relative, then the child will be moved relative to the body element.