I took this picture on my holiday but unfortunately I didn't notice that there was a person in the background. Would it be possible to remove the woman with the black hair and the blue skirt in the background?
You can improve on the same job if you want to, my friend.
Here is what you need to improve - observe her hand and railing how they interact with the water in contrast to their interactions elsewhere? Also how the skirt interacts with the water in the top of railing and where you worked?
You need to make those edges sharper. One solution would be to use a harder edge brush or to use a mask while working.
I would suggest you work on this image and post it in "Show your work" section, asking for further critique. That is the only way to improve. All the best, my young friend.