What does integer `e` represent in the `PrivateKey` function?

I am trying to use the private key function here: https://braneproject.gitlab.io/ECC.jl/#ECC.PrivateKey

It says: "PrivateKey(𝑒) represents an S256Point determined by 𝑃 = 𝑒G, where 𝑒 is an integer and G the scep256k1 generator point." but I am confused what e refers too. Any arbitrary int?