To what was the narrato referring when he said "the howl of protests that went up all around the building surprise even me"What does this statement mean

He refers to the surprise or amazement he got from the number of people that protested and the strength of the protest.

It means that the narrator himself is surprised by  the protests.

Explanation:

it is the background information on the characters and setting explained at the beginning of the story. the exposition will often have information about events that happened before the story began. the exposition is often the very first part of the plot.