Imagine you are in a really big building, like a castle or a very old church. And inside this building, there is a long hallway that goes along the side of the big room where people sit and pray. This hallway is called the soutra aisle.
In the olden days, people used to read books to learn about medicine and healing. And sometimes, they would read these books out loud to other people who were sick. They would do this in the soutra aisle because it was a quiet place where they could speak without disturbing the people who were praying.
This hallway was also used to show off beautiful things like paintings, statues, and other decorations that people would give to the church. People would walk through the soutra aisle and admire all the pretty things.
So basically, the soutra aisle is a long hallway in a big, old building where people used to read medical books and show off pretty decorations.