$ df -h ( hit enter )

Will return something similar to:

Filesystem            Size  Used Avail Use% Mounted on
/dev/sda5             128G   80G   47G  64% /
/dev/sda2             2.0G  264M  1.6G  15% /tmp
/dev/sda1              99M   23M   71M  25% /boot
tmpfs                  16G     0   16G   0% /dev/shm