بِسْمِ اللَّهِ الرَّحْمَٰنِ الرَّحِيمِ
Alif. Laam. Miim.
-Sura Al-Baqarah, Ayah 1
This is an example of mutashabihat (unclear/ allegorical) verses.
Some scholars interpreted them, some didn’t.
One of the wisdom of Allah using these types of phrases is to attract Arabic listeners. It is uncommon to construct an ayah only with disconnected letters. Furthermore, it emphasised that this Qur’an is revealed in Arabic language, similar to the language they use everyday, and their inability to produce similar chapter to it proved that this Qur’an is divine.
Allah knows best.