Someone is trying to gain access, how do I stop it?

So i’m about a week into my first Digital Ocean droplet and my first server ever. I got a droplet mostly to learn the ropes and host a couple services (VPN, Teamspeak, SSH). I checked out the auth.log yesterday and noticed that someone is trying to gain access to my server (I think using brute force?). This is what my auth.log file looks like and has been going on for two days now here. I have SSH enabled so I’m pretty sure I am the only one who can gain access since I am the one who has the private key but I want to know if this person who is trying to gain access can somehow get around it or if it is causing any harm to my droplet? Also, I don’t know if it helps or not but the only user on my droplet is the root server right now and I have password authentication turned off so that you have to have the SSH key.