... or at least can explain me how to do it. Thanks in advance.
It's a fairly laborious, time-consuming job that requires patience. You need to replace the lettering with what should be behind it, which contains a lot of different textures, tones and gradations, particularly in the folds of the leather jacket and in the tiles behind the letter U. The main tool would be the Clone Stamp, followed by the brush tool where you carefully paint-in the colors (always on new layers) to essentially re-draw the image and have it blend convincingly with the rest of the photo. For the clone stamp, you need to sample often and do very small areas at a time. The letter A is the easiest to cover up, but the rest of it will take patience.
In this particular image, the lettering happens to be both white and translucent, which allows a trick to give you a head start:
1. Make a selection of the white lettering (it doesn't need to be perfect) and copy it to a new layer.
2. Change the layer blend mode to Multiply, which I've done in the second image below. You'll still need to use the clone stamp extensively, but it makes life a bit easier starting from here vs. the original image.