If you only can choose 1 skill to learn, then I will say "presentation skill" is a must have. I do learn about this skill some time before graduate and I feel lucky with my choice. Setelah beberapa tahun berkarir, all of my job required this skill and I think it's good to share how it looks like from a 過來人 perspective 🙂 People said you will understand something after go through it - yes, I feel it.
I'm not a natural born speaker and an introvert before, you can read how I solve it here if you haven't. (Read : How an introvert being open minded?)
What is the different within presentation & communication?
Presentation most likely you are transferring some information to audience with some visual display which content some business update, some knowledge, or some sharing. While communication is fully by verbal only. In simple way we can say, presentation including communication.