@Virginia7....Yeah Virginia, the BNB bit is a bit of a euphomism! In general those who do provide some sort of breakfast will be those who host in their own house and do NOT have multiple listings. It's up to you, some hosts are making a nice bit of extra money on the side by charging for and providing meals for guests.....not just breakfast but evening meals. I have even seen on the CC in 'The Living Room' thread, lovely menus that hosts like @David & Fiona in the Phillipines are providing for their guests. At times I do it myself for our hosting. I select meals that are easy to 'finish' and can be easily adapted to suit dietary requirements like Chicken, Mushroom, Pumkin, Asparagus Risotto.......or Chicken, potato, Leak and Thyme individual pies. These dishes are absolute winners and cost next to nothing to prepare.
All I will say is, if you decide to offer a full hosting experience including the provision of some meals it will guarantee you 5 star reviews!!!
Good luck Virginia.....cheers....Rob