Fungal things have something to do with a fungus, or an organism that produces spores. The most familiar fungal species are mushrooms.
Yeasts and molds are fungal, and if you see a mildewed area on the wall of your shower, you can say, "Will someone please clean this fungal mess?" The fungal organisms that bear fruit are mushrooms, which you might think of as plants but which really exist in an entirely separate category from plants and animals. Fungal and fungus both come from the Latin, with the probable Greek root sphongos, "sponge."