How should I decorate a wall in the balcony of my resort?

where is it? What view do you have? You could put up a wall fountain, tiled back, or glass. Maybe some climbing vines, with a lovely scent and nestle some fairy lights among them. Surrounding fountain. Or a mural, painted or mosaic, that reflects your environment, ocean waves, floral, sunrise/set...

Tile or a mural would be my choice. I'd stay away from any kind of vine. They're very invasive and will break down the exterior. They get into everything. Plus, they are very hard to get rid of.

I would do a wall fountain. Something that would bring the water up to the balcony.

You could add wall sconces with a trailing vine - that you would have to look around & see what is native to the area & be very aware of it trying to root into walls.

How about a mural with tiles and then have some potted plants that can be removed during the winter.

Since you're on the sea, I would suggest Shiplap in white. placed horizontally on the wall. Shiplap is very beachy and all the rage on Cape Cod and Fire Island and the Hamptons. It's not a fad and it's what the old beach houses had and always painted white. Great on the ceiling too. Look up the high end beach cottage sites on "Shiplap". Wonderful and you can hang things like a large metal compass and such. I like Maritime Salvage sites for old ship's lights. Great look. Remember placed horizontally is the way to go. Good luck.

We live on the water and like the multicolored tile mosaic animals on our walls. We have collected them in our travels but we got a sea turtle in Key West and an iguana in Barcelona. I’m sure they are available online but I like to see and choose the colors in person. Also, we are trying to keep the scale since we like to clump them together. Have fun with it! I have also seen some cool fire or water walls on Amazon. They are much more contemporary than fountains.

Seashells filled with bromeliads and drift wood as shelves for finds ie: sea glass, starfish.. keep it simple and light - perhaps a turtle made of resin, bring the sea onto the patio