Interpret fdisk output for HPE ProLiant ML350

I am a newly baked server owner and I bought the above mentioned model which nominally has 4*1.2TB of physical disks. I was wondering if my amateurish ubuntu installation "caught" them all. I have however some trouble interpreting the output of fdisk:

> sudo fdisk -l Disk /dev/sda: 2.2 TiB, 2400419667968 bytes, 4688319664
> sectors Units: sectors of 1 * 512 = 512 bytes Sector size
> (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal):
> 262144 bytes / 524288 bytes Disklabel type: gpt Disk identifier:
> 0A98A329-82EB-40C1-B70D-E686833D31C2
> 
> Device       Start        End    Sectors  Size Type /dev/sda1     2048
> 1050623    1048576  512M EFI System /dev/sda2  1050624    2549759   
> 1499136  732M Linux filesystem /dev/sda3  2549760 4688318463
> 4685768704  2.2T Linux LVM
> 
> 
> Disk /dev/sdb: 512 MiB, 536870912 bytes, 1048576 sectors Units:
> sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512
> bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes
> Disklabel type: dos Disk identifier: 0x00000046
> 
> Device     Boot Start     End Sectors  Size Id Type /dev/sdb1       
> 2048 1048575 1046528  511M  c W95 FAT32 (LBA)
> 
> 
> Disk /dev/mapper/sciencedb--vg-root: 2.2 TiB, 2398089117696 bytes,
> 4683767808 sectors Units: sectors of 1 * 512 = 512 bytes Sector size
> (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal):
> 262144 bytes / 524288 bytes
> 
> 
> Disk /dev/mapper/sciencedb--vg-swap_1: 976 MiB, 1023410176 bytes,
> 1998848 sectors Units: sectors of 1 * 512 = 512 bytes Sector size
> (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal):
> 262144 bytes / 524288 bytes

Could you elucidate me?

Thanks!