To see status of all the ZFS Pools, all arrays in ZFS is referred to as a pool.

zpool list

returns:

NAME           SIZE  ALLOC   FREE  CKPOINT  EXPANDSZ   FRAG    CAP  DEDUP    HEALTH  ALTROOT
Pool1         43.5T  35.6T  7.94T        -         -    10%    81%  1.00x    ONLINE  /mnt
freenas-boot   216G  5.08G   211G        -         -     0%     2%  1.00x    ONLINE  -