You could explain that the father's sperm comes into ffie mother through the father's penis. Your child's early sexual concerns and questions may be about the differences between men and women. You can help your child learn that boys and girls are born with different genitals. Your toddler should know the correct names for his body's sexual parts. Teach him these as you teach him the names of other body parts.
All young children handle their genitals.
Normal children like to explore all parts of their bodies. When they handle their genitals and find that this feels good, they may rub them. They may masturbate when they feel bored or upset. Some masturbation does no harm. It is normal and it is best to ignore it.