Emptiness = true essence of dharma
Forms of dharma = illusion being
Essence of dharma = consciousness
Dharma = consciousness and the appearance of all life form.
Dharma has the power to cover all.
There are many definitions of Dharma
For example: Teaching Dharma: Whatever can teach you eternal wisdom is called teaching Dharma, mantra, sutra, even statue can teach.
Whatever make you understand life in all complete angles.
But in this case above we talk about Dharma in the simplest way, two directions, essence and appearing form. Dharma has these both sides.
One is the original power, the force of life.
Then that force of life create appearing form, called illusion being.
Empty itself has many meanings. See the post below.
But empty here means something that exists without form.