Sexual Intercourse (sexual penetration) with a child is Child defilement.

Safety tips for children or girl against rape:
Children must know that every part of their body is private and should not be touched except for care and cautious affection.
Children should be taught to play their role in their Personal Safety and Self Protection
Children should keep their private spaces
Children should be encouraged to speak up at the slightest suspicion of impending abuse
Children should also speak in the unfortunate incidence that abuse occurs
Children should be taught to understand the principles of self-protection and how the abuser thinks

Penalty: (State applicable laws and jurisdiction)
By virtue of the Child’s Right Act and for many states that have domesticated the law, any person who has sexual intercourse with a child commits a felony and is liable on conviction to imprisonment for life.
By Section 282 (1b) of the Penal Code Act (Applicable in the North), and Section 218 and Section 221 of the Criminal Code Act (Applicable in the South), life imprisonment is the punishment for child defilement. Under the Criminal Code Act, this is applicable when the child is under 13 and 14 under the Penal Code Act.
Where the child above 13 and under 16 under the Criminal Code Act, the offender is liable to imprisonment for two years with or without caning.
In Ogun and Delta State, the law provides for life imprisonment for persons under 11 years and not 13years