Warning: Cannot Modify header information - headers already sent by - Does anyone know how to resolve this error in Wordpress?

Question

I am beginner in Wordpress, I would like a help to resolve this error. Warning: Cannot Modify header information - headers already sent by (output Started at public_html/wp-includes/functions.php:74)pluggable.php on line 1296

   71 function current_time( $type, $gmt = 0 ) {
  72    // Don't use non-GMT timestamp, unless you know the difference and really need to.
 73     if ( 'timestamp' === $type || 'U' === $type ) {
// linha74          return $gmt ? time() : time() + (int) ( get_option( 'gmt_offset' ) * HOUR_IN_SECONDS );
        }
    
        if ( 'mysql' === $type ) {
            $type = 'Y-m-d H:i:s';
        }
    
        $timezone = $gmt ? new DateTimeZone( 'UTC' ) : wp_timezone();
        $datetime = new DateTime( 'now', $timezone );
    
        return $datetime->format( $type );
    }