Look at www.emulation64.net, click on the english flag on the upper-left conrner and then look at the newest post which says "Safeguard of ZZelda, Ocarnina of Time:" and it says it will enable you to arrive directly at the last castle of the play: "The Tower of GAnnon. Ther it will show you a screenshot.
Now, to answer your question, it is simply a bad translation "safeguard" apparantly came from "savestate" somehow... So, they mean savestate on that website, not safeguard.