SMART Errors: What does it mean?

[Linux for blind general discussion]

This is an error report from
smartctl -a /dev/sda
Truncated, showing only intro and error section
smartctl 6.6 2016-05-31 r4324 [x86_64-linux-4.18.0-0.bpo.1-rt-amd64] (local build)
Copyright (C) 2002-16, Bruce Allen, Christian Franke, www.smartmontools.org

=== START OF INFORMATION SECTION ===
Device Model:     HITACHI HUS724040ALE640
Serial Number:    PAGRGBRS
LU WWN Device Id: 5 000cca 22bca3623
Firmware Version: MJAONS04
User Capacity:    4,000,787,030,016 bytes [4.00 TB]
Sector Sizes:     512 bytes logical, 4096 bytes physical
Rotation Rate:    7200 rpm
Form Factor:      3.5 inches
Device is:        Not in smartctl database [for details use: -P showall]
ATA Version is:   ATA8-ACS T13/1699-D revision 4
SATA Version is:  SATA 3.0, 6.0 Gb/s (current: 6.0 Gb/s)
Local Time is:    Fri Apr  5 02:43:04 2019 CDT
SMART support is: Available - device has SMART capability.
SMART support is: Enabled

SMART Error Log Version: 1
ATA Error Count: 65535 (device log contains only the most recent five errors)
	CR = Command Register [HEX]
	FR = Features Register [HEX]
	SC = Sector Count Register [HEX]
	SN = Sector Number Register [HEX]
	CL = Cylinder Low Register [HEX]
	CH = Cylinder High Register [HEX]
	DH = Device/Head Register [HEX]
	DC = Device Command Register [HEX]
	ER = Error register [HEX]
	ST = Status register [HEX]
Powered_Up_Time is measured from power on, and printed as
DDd+hh:mm:SS.sss where DD=days, hh=hours, mm=minutes,
SS=sec, and sss=millisec. It "wraps" after 49.710 days.

Error 65535 occurred at disk power-on lifetime: 1335 hours (55 days + 15 hours)
  When the command that caused the error occurred, the device was active or idle.

  After command completion occurred, registers were:
  ER ST SC SN CL CH DH
  -- -- -- -- -- -- --
  84 51 90 d0 bb 03 0d  Error: ICRC, ABRT at LBA = 0x0d03bbd0 = 218348496

  Commands leading to the command that caused the error were:
  CR FR SC SN CL CH DH DC   Powered_Up_Time  Command/Feature_Name
  -- -- -- -- -- -- -- --  ----------------  --------------------
  61 00 c0 80 b6 03 40 00      10:34:04.997  WRITE FPDMA QUEUED
  61 00 b8 80 b1 03 40 00      10:34:04.997  WRITE FPDMA QUEUED
  61 e0 b0 80 bb 03 40 00      10:34:04.997  WRITE FPDMA QUEUED
  ef 10 02 00 00 00 a0 00      10:34:04.997  SET FEATURES [Enable SATA feature]
  ec 00 00 00 00 00 a0 00      10:34:04.995  IDENTIFY DEVICE


There are 5 more of these. What is this error telling me, exactly? I don't quite get it.