This is an interesting species of Justicia and a member of the broad Acanthaceae family of plants. Its natural habitat includes India and tropical east Africa. It is sometimes called the white shrimp plant or squirrel's tail. Its summer blooms are held in slim upright spires and are comprised of papery, green-veined white bracts enclosing pale pink flowers. It is very effective grown with white-variegated foliage plants nearby as illustrated below; I also like it with very dark foliage (such as a purple-leaved Canna hybrid for drama).
It grows to around 1 m in height. It needs to be cut back hard in late winter and tip-pruned as it grows through spring and early summer, to promote a compact shape, otherwise it can become leggy. It grows OK in part shade though mine flowers much better in a sunny spot. It can tolerate dry soil. It is resilient to hot summer weather in Sydney.
Note that this plant can become weedy in subtropical and tropical climates, so should probably not be grown in gardens in these regions.