Hola.
They look like quince (membrillo) to me. They are tart and hard consistency unless you cook them.
Peel and uncore them, then make big wedges and maybe spray them with some lemon juice, just a bit to avoid oxidation (not necessary but they look better if do not darken too much). Cook them gently in a skillet with finely sliced onions, some mild spices as cardamom and cloves or mild Moroccan blend, some cinammon (a stick the better), and finally add some honey to caramelize (do not burn it). Nice with lamb (you can search for lamb + quince tagine recipes).
You can also make quince jelly/preserve (carne de membrillo) with them if you have some kilos.
Best regards from Spain,
Rafa