What is sexual penetration? is it when a males penis enters inside a woman's vaginal hole?

Depends on details: Different people can have differing views of what penetration is. From a legal standpoint, penetration probably means entering the airspace. That would mean being in the airspace between the labia even if not touching anything and not going through a hole yet. It's like a foreign plane flying across the Atlantic and ending up in US airspace, but not landed yet. The plane already penetrated the US.