As a Baha’i’, I do not practice Islam, but I do read the Qur’an. I am curious about the Islamic interpretations of the this sequence of letters from the surah «Mary.» It is the first Aya, if memory serves.
Sequences like this are called the Huruf al-Muqatta'at. You can research that. There are different views on its meaning:
It is from the mutashaabihaat and its meaning is only known to Allah.
It means the sequence of letters themselves. They are being sworn upon, similar to how other things are sworn upon.
The letters stand for some names/attributes of Allah. For example it is reported that:
Kaaf stands for Kafee or Kabeer or Kareem or Malak ,
Haa stands for Haadi or Haad or Allah
Yaa stands for Yameen or for Yujeeru wala yujaru Aaalayhi or for Yadu Allahi fawqa aydeehim or Ameen or Hakeem or Azeez or Raheem
Ayin stands for 'Aalim or 'Azeez or 'Azeem or 'Alee or 'Adl
Saad stands for Sadiq or Samad or Musawwir
It can then mean that Allah is Sufficient, Guide, Protector, All-Knowing and Truthful in His promise etc.
It is by itself a name of Allah. Or each letter is by itself a name of Allah.
It is a name of the Quran.
It is a name of the Surah.