The baby will be female.
Explanation:
There are two chromosomes, X and Y. If a baby is born with two X chromosomes, the baby will be female. If a baby has one X chromosome and one Y chromosome, the baby will be male.
These will be in the 23rd pair of chromosomes, or the sex chromosomes. There are also conditions in offspring where a baby will be born with the chromosomes YY, but this is rare.
