# As the hosts of heaven cannot be counted
"As the hosts of heaven are so many that they cannot be counted"
# the hosts of heaven
"the armies of heaven" or "the multitude of things in the sky". This refers to the sun, moon, stars. They are called the hosts because there are so many of them, just as armies have many soldiers.
# as the sand of the seashores cannot be measured
"as the sand of the seashores is so abundant that it cannot be measured"