How add nofollow in website link?

You can use the available filters to adjust the output of the testimonial content.

For your particular case, you could add the following to your theme’s functions.php file. This will target only the details section (company name/tagline and website URL). Leaving the below as is, will add the rel=”nofollow” tags to the website link.

function custom_testimonial_details( $shortcode_output, $options) {

	$shortcode_output = '<div class="bne-testimonial-details">';

		// Tagline/Company Name Only
		if ( empty( $options['website_url'] ) ) {
			$shortcode_output .= '<span class="bne-testimonial-tagline">'.$options['tagline'].'</span>';
		}

		// Website URL Only
		if ( empty( $options['tagline'] ) ) {
			$shortcode_output .= '<span class="bne-testimonial-website-url">'.$options['website_url'].'</span>';
		}

		// Tagline/Company Name and Website URL
		if ( !empty( $options['tagline'] ) && !empty( $options['website_url'] ) ) {
			$shortcode_output .= '<span class="bne-testimonial-website-url">'.$options['tagline'].'</span>';
		}

	$shortcode_output .= '</div><!-- bne-testimonial-details (end) -->';

	return $shortcode_output;
}
add_filter( 'bne_testimonials_details' , 'custom_testimonial_details' , 10 , 2);

You can also adjust the above markup if needed.