The term Niranjan Nirankar Swaroop refers to the Satpanth idea (found in the Ginans of the Ismaili religious tradition) that the true spiritual teacher is esoteric and all-pervading. It was founded by the Mureed when meditating upon special mantras given by the exoteric spiritual teacher (Bandagi).
Meaning of Each Individual Word
Niranjan = "that which cannot be seen by mortal eyes." Hence one can only experience the spiritual guide.
Nirakar = "that which is without material form." Hence reinforcing the belief in the true guide being non-corporeal.
Swaroop = Made of Swa and roop, Swa means own and roop means form. So in this case the Swa means divine self and roop means divine form. Meaning that Niranjan Nirankar manifests itself willingly without losing its original divine form or divine origin. Hence, the spiritual guide can become manifest in human form without the human form being less than the spirit form.
To cross religious terms, Jesus would be considered a manifestation of the Swaroop of God, Swaroop in other words is incarnation.