更に【さらに】

更に means "even more", "further": a level already reached goes up another step. It goes before an adjective or a verb. It is often written in hiragana, さらに.

Before an amount, it means "another", "more on top": さらに更にいちじかん一時間まった待った is "I waited another hour".

更に or もっと

もっと is the everyday word for "more". 更に is more formal and says something has already reached one level and goes past it. In writing, reports and speeches, 更に is the usual choice; with friends, もっと.

"Furthermore"

At the start of a sentence, often with a comma after it, 更に adds a further point to what has just been said: "furthermore", "what's more". This use belongs to writing, news and presentations.