One example is illustrated on this sign that I photographed in Bogota two years ago. It is advertising a new apartment complex that will have two elevators, a garbage chute, and two social halls or community rooms that are also common in some apartment complexes here in the US. If I hadn't sounded out the word "shut" the way a Spanish-speaking person would, I never would have figured out that it meant "chute." "Shut" is the English word spelled phonetically in Spanish, though the "sh" sound does not exist in Spanish except in countries in southern South America such as Argentina, Uruguay and Chile, and where the sound does exist, it is never spelled "sh" except perhaps in a word borrowed from another language.
Another even more important example is the word "muchacha," where not knowing how the word is used could create problems. If I had only paid attention to my high school Spanish textbook, I would have assumed that the word always meant girl or young woman. However, "muchacha" could also mean maid or servant girl, and maids sometimes dislike the use of the word when referring to them, preferring the terms "empleada doméstica" or "empleada de servicio" (female domestic or service employee).
See my language learning webpage for more tips.