Did the Prophet (peace and blessings be upon him) have maternal uncles, meaning brothers of his mother, Aminah bint Wahb, and if he did not have maternal uncles, then how do we understand verse 50 from Surat Al-Ahzab, which mentions "and daughters of your maternal uncles and daughters of your maternal aunts"?

The Prophet, may Allah bless him and grant him peace, had no maternal uncles except one, Abd Yaghūth, and he had no maternal aunts.

The meaning of "the daughters of your maternal uncle and the daughters of your maternal aunts" in the verse refers to his mother's clan from Banū Zuhrah. It is common to refer to close and distant relatives on the mother's side as "maternal uncle" (khāl) and "maternal aunt" (khālah).

Sad ibn Abī Waqqās, may Allah be pleased with him, was from the sons of the paternal uncle of the Prophet's mother, may Allah bless him and grant him peace. That is why the Prophet, may Allah bless him and grant him peace, called him "my maternal uncle," not meaning that he was his mother's brother.