まるで〜のようだ
Just as ifmachine translation
Formationまるで + noun + のようだ／のように + …；まるで + clause + ようだ／みたいだ
まるで sits in front of a simile to push it to the maximum: "just as if, exactly like." It pairs with 〜ようだ・〜のように・〜みたいだ, which you've used fluently since N4: 今日は暖かくて、まるで春が来たようです (it's warm today, just as if spring had come). On hearing まるで, the listener knows immediately that what follows is a simile, not reality.
The pattern is at its most powerful when the contrary fact is stated explicitly in the sentence: 彼は日本人ではないのに、まるで日本人のように話す (he isn't Japanese, yet he speaks just like a Japanese person). This "〜のに、まるで〜" structure is well worth imitating in your writing.
Note one other meaning: まるで followed directly by a negative means "not at all": まるで分からない (I don't understand at all). In this meaning no ようだ follows — don't mistranslate it as a simile.
Examples
今日は暖かくて、まるで春が来たようです。
It's warm today, just as if spring had come.
彼は日本人ではないのに、まるで日本人のように話します。
He isn't Japanese, yet he speaks just like a Japanese person.
初めて雪を見たとき、まるで夢の中にいるようでした。
When I saw snow for the first time, it was as if I were in a dream.