Object Oriented Programming - Understand Own Properties

Tell us what’s happening:
I dont really have an issue. It was easy to understand, but I’m just wondering, what is the use of ‘Understanding Own Properties’. Can someone give me an example when I’d be using this? It sounds interesting but I’m having some trouble figuring out what to use this for.

Your code so far

function Bird(name) {
  this.name = name;
  this.numLegs = 2;
}

let canary = new Bird("Tweety");
let ownProps = [];
// Only change code below this line

*Solution deleted*
  }
}

console.log(ownProps);

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Challenge: Object Oriented Programming - Understand Own Properties

Link to the challenge:

you will need to use this soon enough in the fcc challenges.
But in general, it is to check that the property is defined.