I have an external 1TB Seagate Harddrive but it shows that only 268MB is available. Why?

I tried to erase it with Disk Utility but unsuccessful. It still shows that only 268MB is available, while another utility program (balenaEtcher) used for writing image files, shows 1TB free space. How to make it to display 1TB in Disk Utility?

/dev/disk0 (internal):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                         500.3 GB   disk0
   1:             Apple_APFS_ISC ⁨⁩                        524.3 MB   disk0s1
   2:                 Apple_APFS ⁨Container disk3⁩         494.4 GB   disk0s2
   3:        Apple_APFS_Recovery ⁨⁩                        5.4 GB     disk0s3

/dev/disk3 (synthesized):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      APFS Container Scheme -                      +494.4 GB   disk3
                                 Physical Store disk0s2
   1:                APFS Volume ⁨Macintosh HD⁩            15.1 GB    disk3s1
   2:              APFS Snapshot ⁨com.apple.os.update-...⁩ 15.1 GB    disk3s1s1
   3:                APFS Volume ⁨Preboot⁩                 439.1 MB   disk3s2
   4:                APFS Volume ⁨Recovery⁩                1.0 GB     disk3s3
   5:                APFS Volume ⁨Data⁩                    231.6 GB   disk3s5
   6:                APFS Volume ⁨VM⁩                      20.5 KB    disk3s6

/dev/disk6 (external, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:     FDisk_partition_scheme                        *1.0 TB     disk6
   1:                 DOS_FAT_32 ⁨FV⁩                      268.4 MB   disk6s1
   2:                      Linux ⁨⁩                        8.5 GB     disk6s2
                    (free space)                         991.5 GB   -

Solution 1:

I found a solution to this problem. I had to first attach the hard-drive to Windows 10 and delete the last two volumes in /dev/disk6 (DOS_FAT_32 "FV" and Linux) through Windows disk management. After that I attached it back to the Mac and via disk utility erased it one more time with structure APFS.

/dev/disk0 (internal):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                         500.3 GB   disk0
   1:             Apple_APFS_ISC ⁨⁩                        524.3 MB   disk0s1
   2:                 Apple_APFS ⁨Container disk3⁩         494.4 GB   disk0s2
   3:        Apple_APFS_Recovery ⁨⁩                        5.4 GB     disk0s3

/dev/disk3 (synthesized):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      APFS Container Scheme -                      +494.4 GB   disk3
                                 Physical Store disk0s2
   1:                APFS Volume ⁨Macintosh HD⁩            15.1 GB    disk3s1
   2:              APFS Snapshot ⁨com.apple.os.update-...⁩ 15.1 GB    disk3s1s1
   3:                APFS Volume ⁨Preboot⁩                 439.1 MB   disk3s2
   4:                APFS Volume ⁨Recovery⁩                1.0 GB     disk3s3
   5:                APFS Volume ⁨Data⁩                    231.7 GB   disk3s5
   6:                APFS Volume ⁨VM⁩                      20.5 KB    disk3s6

/dev/disk4 (external, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *1.0 TB     disk4
   1:                        EFI ⁨EFI⁩                     209.7 MB   disk4s1
   2:                 Apple_APFS ⁨Container disk5⁩         1000.0 GB  disk4s2

/dev/disk5 (synthesized):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      APFS Container Scheme -                      +1000.0 GB  disk5
                                 Physical Store disk4s2
   1:                APFS Volume ⁨Naamloos⁩                1.2 MB     disk5s1