virtualbox – What size of physical hard disk is available in oracle virtual box ? I have 60 GB harddisk but slider gives me the range of 2TB

You may define the disk in the user interface to any size up to 2 TB.
What happens next depends on the type of the disk.

If the disk type is defined as Fixed, the entire amount will be allocated and can fail if not enough free space is available..

With the Dynamic disk type, only as much as is used will be allocated,
so the disk will grow dynamically as its used size increases.
It’s dangerous to define the disk size as larger (or even close)
to the amount of free space.
Some operating systems will fail badly if free space is exhausted.