A more thorough explanation:

Definition: Putting in fear means threatening someone with violence to force them to give up their property. This is considered robbery under common law.

Example: If someone points a gun at a store clerk and demands all the money in the cash register, they are putting the clerk in fear to steal the money.

This definition explains that putting in fear is a way of committing robbery. The example shows how someone can use this tactic to steal from another person.