how to echo a custom taxonomy term from an array of term

You’re checking if a product_type has a term using has_term(). Now you need to actually get the terms using get_terms(). That function can technically return from 1 to 4 terms. If more than one of the terms is set, you’ll need to pick one. In the following code, I chose the first since there’s guaranteed to be at least one term.

if( has_term( [ 'laptop', 'TV', 'phone', 'tablet' ], 'product_type' ) ) {
  //* Get the terms
  $terms = get_terms( [
    'taxonomy' => 'product_type',
    'slug'     => [ 'laptop', 'TV', 'phone', 'tablet' ],
  ] );
  //* There could still be up to 4 terms, so use the first
  echo $terms[0]->name;
}