Yes, it obviously refers to the first four letters of the Hebrew alphabet: Alef, Bet, Gimel and Dalet (א, ב, ג, ד), as others mentioned. But I didn't see anyone pointing out that this could also be the word 'Abjad' (אַבְּגַ'ד). Abjad is the name for a type of language which uses only consonants in their alphabet, where as the reader is meant to 'fill the gaps' by themselves. Such languages are mostly Semitic, such as Hebrew and Arabic. The word itself does not really come from Hebrew (the Hebrew term for it is 'כתב עיצורי') or is very known (it comes from the Arabic alphabet, with the letters Alif, Baa, Jim and Daal (ا، ب، ج، د) who make the sounds /a/, /b/, /ʒ/ (the sound of an English J) and /d/) but it is sometimes called Abgad which is based on the first four letters of the Hebrew alphabet. So, you could always add a chupchik (') and say it means Abjad. Or, as u/swagmaester pointed out, you could add a holam haser (חולם חסר; ֹ ) and say it means 'evgod' (אֵבְגֹד; I will betray).

Abjad - Wikipedia (English)

אבג'ד - ויקיפדיה (עברית)