When used as a legal term, this varies from state to state. In some places it's a temporary license that must be applied for. In others it may be automatically conferred after graduation.
After it is received, the usual situation is that it expires, a) after the nurse passes NCLEX and earns her RN license, b) after the nurse fails the NCLEX, or c), 90 days passes from the date of issuance.
For a nurse to hold a temporary license, there must be the presumption that she will be able to pass NCLEX when she takes it. If she does not pass, that presumption is no longer valid and she is no longer allowed to work as a GN.
But, as I said, check with your state BON to be certain you are following their rules and regs.