I found this tree in Crete, Greece close to the sea, planted next to a building. Since I haven't seen this tree anywhere else in the island, I suppose it was planted by someone. Here are some pictures of it.
Based on the distinctive leaf shape and placement of the fruit along the stem that appears to be a papaya.
If so then the plant should "bleed" latex (a milky white fluid) when damaged. You can test this by breaking off a small piece leaf. Image credit: By Max.kit - Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=54547062
$\begingroup$ Indeed they seem identical. I will break a small piece of leaf tomorrow and I will let you know and accept your answer as correct! Comparing the plant with your photo, mine seem to not be doing so well. Could it be the cold? The temperature varies between 9 and 17 degrees $\endgroup$ Feb 28, 2020 at 20:03
$\begingroup$ Glad I could help! Your plant does look quite damaged, but that could be due to many things including: cold, water stress, nutrient deficiencies, diseases, or pests. ——— If you want to ask a question about that I recommend Gardening & Landscaping. $\endgroup$– tyersomeFeb 29, 2020 at 20:20