In most of the world, if you want to travel from A to B, you buy a ticket from A to B and that's it.
However, in India, it's possible to buy a ticket from X to B, designate a Boarding Point in A somewhere along the way, and board the train at A. Makemytrip explains how this works:
What is a boarding point?
You can choose a boarding point, from where you will board the train. This can be any station between the Reservation From station and Reservation Upto station. By default, you Reservation From station is also your boarding point.
While you may choose a boarding point as any station on the route of the train, you would have to pay the fare as applicable for Reservation From – Reservation To stations. For example, if you are booking a ticket from Mumbai Central to New Delhi and choose the boarding point as Kota Jn, then you can board the train only at Kota Jn and not between Mumbai Central and Kota Jn. You would however have to pay the fare for Mumbai Central to New Delhi
The question left unanswered is why would you want to do this? It would seem much more logical and cheaper to just buy a ticket from Kota Jn to New Delhi.