[My query is about PNR 4664222848 for train 12715 SACHKHAND EXP]
It means that you have been allotted a ticket but have not been allotted a seat or berth. In that case, you cannot get on the train unless the final chart before departure confirms that your seat has been reserved. It’s a first-in, first-out queue of people waiting to get a seat.
You may check the status of your PNR if it is confirmed or not here: