I am studying functional reactive programming and most of all the examples I found is all about streams of events for example Bacon.js. I'm not sure I get these examples. I thought FRP is all about changing one variable and continuous change other affected variables but in a functional way. Is my understanding correct about Functional Reactive Programming?
You are absolutely correct with your understanding of FRP. Apparently, what confuses you is terminology used in Bacon. Since all the mess is really about the event streams, it is not clear from the start how exactly those streams appear and what's their relation to browser events and DOM elements. I had these question too.
To get better understanding of what FRP is, not Bacon, I'd suggest you reading the post Reactive Programming in JavaScript by Sebastiaan Visser in Silk's Engineering Blog.
This reading helped me understand the subject and I more than sure that it'll break things down for you either.
Concerning event streams, think of them as of what you work with when you direct multiple (or single) variable value changes to some object responsible for triggering your callback each time there is an update.