What result does the expression "this.firstName + ' ' + this.lastName" yield in the revealIdentity method?

The expression "this.firstName + ' ' + this.lastName" concatenates the value of the firstName property with a space character and the value of the lastName property.

In a situation where this.firstName and this.lastName are both properly defined and hold string values, this expression will result in a single string that combines the first and last names, separated by a space. For instance, if this.firstName is "John" and this.lastName is "Doe", the expression will evaluate to "John Doe".

This functionality is typical in programming languages that support string concatenation, allowing for the generation of a full name in a formatted way. If either firstName or lastName were to be undefined or not present, the result would still display whatever is available, but given the correct setup where both properties contain strings, the final output will indeed be the full name formatted properly with a space.