The first thing you need to consider is the writer's use of descriptive words and phrases that describe the environment and the characters within that setting. Look at the phrase "rickety, rotting footbridge". What connotation do those words convey? That doesn't seem to be a safe or inviting place. Those words "show" that this character is entering a situation that might present a challenge or threat. The next sentence presents the word "ominous" to describe the impact of the words on a sign that directly tells the reader something in that situation will pose a threat to the character. Often passages don't provide a word that announces the intended effect like this one does. Often passages create an effect through describing rather than stating details, which requires the reader to make inferences.