How to limit the words in search api autocomplete suggestion?
Try below code, and you can trim $label as you want.

/**
 * Implements hook_search_api_autocomplete_suggestions_alter().
 */
function HOOK_search_api_autocomplete_suggestions_alter(array &amp;$suggestions, array $alter_params) {
  $used_labels = [];
  /** @var Drupal\search_api_autocomplete\Suggestion\Suggestion[] $suggestions */
  foreach ($suggestions as $key =&gt; $suggestion) {
    $suggestion-&gt;setUrl(NULL);
    $label = $suggestion-&gt;getLabel();
    $suggestion-&gt;setSuggestedKeys($label);
  }
}