How do I use Signals?

I am new to Construct 3 and I thought signals seemed so powerful and wanted to give it a try. But I could never get it to work. How to use it? The documentation is very vague about it and I cannot find it in example projects.

Failed attempts:

I never really use signal, the times I tried I ran into errors and there were always other ways to solve the problem.

It looks like the signal would be once the Tween event finishes.

Just add a new event

On Tween "" Finished => Set gameOver to True

-If you have multiple Tween events you can fill in the "" with a Tag just be mindful they are case sensitive.

I will try these out. Thanks!