And she said: I saw the Messenger of Allah (peace and blessings be upon him) covering me while I was watching the Abyssinians playing in the mosque. This hadith is agreed upon by al-Bukhari and Muslim.

The Shaykh :"And she (may Allah be pleased with her) said:

I saw Allah's Messenger (ﷺ) at the door of my house screening me while I watched some Abyssinians (Ethiopians) who were playing in the mosque

رأيت النبي صلى الله عليه وسلم يسترني وأنا أنظر إلى الحبشة يلعبون في المسجد

Bulugh al-Maram 2:132

" Yes
Meaning, he was shielding her from the men while she was watching the Abyssinians. The Abyssinians are a part of Africa; people from there who had embraced Islam came to Madinah to learn their religion from the Prophet (peace and blessings be upon him and his family). They were a people of merriment and play, and they could not restrain themselves from playing in the mosque with their spears and arrows.
And her saying the "al" is for mental reference, as mentioned before, meaning the Prophet's (peace and blessings be upon him and his family) mosque. This was during a festival, so 'Umar (may Allah be pleased with him) spoke about them and said: