I assume that you are talking about the Dunbar Hotel in Los Angeles. This was a hotel built in 1928 in LA by an African American who was the first black person to graduate from the dental school at the University of Southern California. If so, this hotel provided mutual aid to African Americans in at least two ways.
First, we should note that the hotel can be considered a part of mutual aid since its owner was an African American. Therefore, anything the hotel does for the black community is mutual aid. The first way in which the hotel helped the black community was by providing jobs. The hotel was built by African American workers. This meant that the hotel provided jobs to people in skilled trades. It also provided jobs to other people who worked there after the hotel was built.
Second, the hotel provided mutual aid in that it gave African Americans a high-quality place to stay. This was in the days of segregation when white hotels would not typically welcome black guests. The Dunbar (or the Somerville, as it was first known) provided a place for African Americans to stay when visiting LA.
A hotel that is owned by African Americans, and which employs them and gives them a place to stay is an example of mutual aid.
I tried to link to a brief history of the hotel, but the link was not accepted. So I will put it here and you can copy and paste if you like.