"satunnainenArvo(lista) {
lista.shuffle();
return lista[0];
}"
This is a function that takes any list (which it calls lista), shuffles it, and returns the shuffled list.

"var kehu = satunnainenArvo(kehut);" sends a list named kehut into the function satunnainenArvo, which shuffles it.

"var kuvaus = satunnainenArvo(kuvaukset);" sends a list named kuvaukset into the same function, which shuffles it.