What are the ambiguous verses (mutashabihat) in the Quran, and what book or website can be beneficial for understanding them?

If the question is about verses that are similar in wording, there is a book titled "Al-Mu'jam Al-Fahras lil-Tarakib al-Mutashabiha Lafzan fi al-Qur'an al-Karim" (The Concordance of Verbally Similar Structures in the Holy Quran) by Dr. Muhammad Zaki. An electronic copy of it can be found online, especially on the "Sayd al-Fawa'id" website.