The output of the 555 drives a transistor that is configured as an oscillator and it gets a pulsed signal. The output of the transistor can be detected up to 200 metres.
The output of the receiver will be a tone and this is picked-off the speaker to illuminate a LED.
Simple is always better. I forgot that AM/FM "pocket radios" are dirt cheap now. Easy to build a little broadcast band one-transistor transmitter and modulate it with the 555 pulses. The circuits were all over the "hobby magazines" in the 1970s, and earlier than that if you built your own two-transistor transmitter. IIRC both AM and FM were popular.
I don't normally recommend that anyone try to build anything from the Instructables website, but
here is a nice little DIY FM transmitter project that mounts to the end of 9 V "transistor radio" battery. It is modulated with an electret microphone, but it would be easy to substitute a 555 oscillator to generate a tone rich in harmonics that would be easy to pick off the speaker in a portable FM radio receiver. I like this particular Instructable because it also has a nice little video showing how to make it, including laying out and etching a tiny circuit board.
And if you want to dig a little deeper, visit Colin Mitchell's interactive website (Google that) for an incredible variety of "stuff" that ranges all over the electronics map. You can even purchase all sorts of electronic kits there, just like on Ebay, from a vendor who speaks English as a native language if that is of any help to you.
Hop