In Terminal execute this command & paste the text here please...
diskutil list
Like...
bd1$ diskutil list
/dev/disk0 (internal, physical):
#: TYPE NAME SIZE IDENTIFIER
0: GUID_partition_scheme *500.1 GB disk0
1: EFI EFI 209.7 MB disk0s1
2: Apple_HFS Macintosh HD 499.2 GB disk0s2
3: Apple_Boot Recovery HD 650.0 MB disk0s3
/dev/disk1 (external, physical):
#: TYPE NAME SIZE IDENTIFIER
0: GUID_partition_scheme *6.0 TB disk1
1: Apple_HFS 1013 1.7 TB disk1s1
2: Apple_Boot 650.0 MB disk1s2
3: Apple_Boot 650.0 MB disk1s3
4: Apple_HFS 1012 401.3 GB disk1s4
5: Apple_Boot 650.0 MB disk1s5
6: Apple_HFS 10.10 505.4 GB disk1s6
7: Apple_Boot Recovery HD 650.0 MB disk1s7
8: Apple_HFS 10.9 749.6 GB disk1s8
9: Apple_HFS 10.11 750.1 GB disk1s9
10: Apple_HFS 10.6 550.1 GB disk1s10
11: Apple_HFS 10.8 579.3 GB disk1s11
12: EFI 209.7 MB disk1s12
13: Apple_HFS 10.7 750.1 GB disk1s13