$_POST fields

  $MyPostField = '';
  if (isset($_POST['MyPostField']))
    $MyPostField= sanitize_text_field($_POST['MyPostField']);

esc_html()

  $BackButtonName = esc_html($categories[0]->name);

Translated text

esc_html_e( ‘This is somewhat embarrassing, isn’t it?’, ‘kleo’ );

esc_url()

  $BackLink = 'href="' . esc_url(get_category_link( $categories[0]->term_id ) ) . '"';