Sure. As you can see on the syncthing-gtk github, there are Ubuntu .deb packages available from the WebUpd8 PPA.
So, first add the PPA. Run this command in Terminal:
sudo add-apt-repository ppa:nilarimogard/webupd8
Type in your password, and follow the instructions to add the repository.
Then update apt by running:
sudo apt-get update
Now you can install syncthing-gtk by running:
sudo apt-get install syncthing-gtk
Again follow the instructions in the Terminal to complete installation.
When completed, you can launch Syncthing-GTK however you normally launch applications… perhaps the Dash, or Applications Menu.
Once you’ve started Syncthing-GTK it will run the First Run Wizard to configure Syncthing on your computer. It will download and install Syncthing Core for you.
There are lots of options available, such as launching Syncthing automatically on login, or Files browser integrations (right-click to share with Syncthing)
Once Syncthing is configured and running correctly, you can add folders to share!
Let me know if you have questions or if anything is unclear. Good luck!