As known to all, Allah means God, while Banda has many meanings. Banda is nowadays used for any man, while earlier Banda was used mostly for a servant or a slave. In this context, banda means a devotee to God. Hence, the phrase Allah ke Banday, which means Devotees to God.
But at the same time, if you go by the popular meaning of the word where Banda can be any man, or rather, any human, Allah ke Banday can also mean God's humans, or humans made by God, which would simply mean Humans. Basically it depends on the context as to which meaning would you like to take here.