Question

fix the one word that is used incorrectly.

snakes will usually not harm you if you let them alone and keep a safe distance

from them.

Explanation:

The incorrect phrase "let them alone" is a misusage. The standard English idiom meaning to refrain from disturbing someone/something is "leave them alone".

Answer:

Change "let" to "leave". The corrected sentence is: Snakes will usually not harm you if you leave them alone and keep a safe distance from them.