How does the law of conservation of energy show the total energy in a system stays the same? plz answer the truth

Law of conservation states that energy in a isolated environment, this basically means that energy cannot be destroyed or created.

I'm citing a site that will give you some great examples and has a decent explanation

https://www.explainthatstuff.com/conservation-of-energy.html

if two electrons have the same n, the same ℓ, and the same ml, then they are in the same orbital. the pauli exclusion principle states that no two identical fermions (a fancy word for electrons and other subatomic particles like electrons) may occupy the same quantum state in an atom simultaneously.