How to prove the legality of a document signed using Adobe Sign?

Hello,

I can't seem to grasp the concept of electronic signature, and that will make me unable to explain it to any legal entity when necessary. I'm not living in the US nor in Europe, and the act of electronic signature is not common at all.

I received an agreement through Adobe Sign, this agreement is for selling a website I own to a foreign investor. I know that I can sign by typing, drawing, or using an image. And after signing, both parties will receive a PDF copy of the signed agreement.

However, when I have to show the agreement to my bank or to the court, how shall I prove that this is a legit agreement signed by the 2 parties mentioned, and not just a document I have written myself and drawn fake signatures on it.

I will really appreciate any help because the matter is somewhat urgent.

Thank you!