How is the @forelse interpreted in Laravel and what is it used for?

It's the same as a foreach, but in case the input parameter is empty, it will show whatever is between @emptyand @endforelse.

The goal of @forelseis to reduce the code needed to do:

@if ($users->count())
  @foreach ($users as $user)
    <p>Usuario {{ $user->id }}</p>
  @endforeach
@else
  <p>No hay usuarios.</p>
@endif

to this:

@forelse ($users as $user)
    <p>Usuario {{ $user->id }}</p>
@empty
    <p>No hay usuarios.</p>
@endforelse

In case you want to see how the Blade compilation is done: https://github.com/laravel/framework/blob/5.4/src/Illuminate/View/Compilers/Concerns/CompilesLoops.php#L14

With an example it is understood, it simply goes through all the values ​​of the array/collection that you pass to it and if it is empty the else is skipped.

@forelse($array as $objeto_individual)
   <h1> {{ $objeto_individual }}</h1>
@empty
   <h1> Sin valores </h1>
@forelse

To complement @Shaz's answer:

It forelsenot only checks if the variable is empty, but also if it is set, that is, it validates "empty"e "isset".