The hexagonal shapes are probably lens flare (considering the weather conditions on the day it was shot) or could be the result of some dirt getting into the camera or onto the lens (considering the environment in which it was shot). The Panasonic Lumix DMC-FZ18 is also getting on a bit now - it was released 14 years ago - so it's likely that the camera is more susceptible to light aberrations than you would expect in modern compact cameras. You might want to think about investing in a lens hood to try and prevent this happening again.
Back to the image you've posted - even though it's not the best quality image (in terms of resolution) - you can get a reasonable result in a very short time using the Spot Healing Brush intially, and then the Healing Brush to tidy up afterwards.
Look at the Photosohop Elements User Guide to see how to work with these tools:
Klar ist das Bild "schlecht" Ich habe extra für die Veröffentlichung nur einen Ausschnitt gewahlt und die Grösse reduziert. Diese "Ringe" werden auch nur angezeigt, wenn ich es mir dem Kontrast "übertreibe". Ic h weiss, dass die FX-18 "alt" ist, aber für meine Zwecke waren die Bilder gut genug. (Einfügen in ein Full-HD-Video, 1920x1080))
Aber dein Vorschlag zum Korrigieren ist genau richtig.
Of course the picture is "bad". I have chosen only a section and reduced the size especially for the publication. These "rings" are also only shown when I "overdo" it with the contrast. I know that the FX-18 is "old", but for my purposes the pictures were good enough. (Insert into a full HD video, 1920x1080))