Disk and partitions in diagram, size (Mb) and mounting points (directories):

lsblk

Lists all block devices, UUID and partition:

lsblk -f

Block devices, UUID and attributes (issues with unpartitioned):

blkid

Cfdisk is an interactive app for disk partitioning. It lets you create, delete, and modify partitions on a block device.

for current disk:

cfdisk

or selected disk:

cfdisk /dev/your.disk

Parted is partition manager which can output brand, model of your disks, their Size (Gb) , file system etc.

parted -l

Partitions with usage (%) and available space:

df

Partitions and types, space (Gb/Mb) and sectors:

fdisk -l

Sfdisk gives disk size (Gb & bytes), sectors, partition type

sfdisk -l /dev/your.disk

When used without argument, is a partitioning tool

sfdisk /dev/your.disk