How does an antenna pick up tv signals?

The short answer is , metal antenna elements are tuned by length and diameter to resonate at a electro magnetic frequencies of the tv channels. The vibrating electrons vibrate each other , even over long distance. Some every day examples of this are , electric guitar , the electrons in a vibrating metal string vibrate the electrons in the electro magnet under the metal string, and this vibrating electron energy is connected to a amplifier.

A simpler example is a 'toaster' , the vibrating 'electrons/electric' flowing through the wires in the toaster make the electrons in the wires vibrate very fast and with a lot of energy and this is high rate of friction between the electrons makes heat. Friction makes Heat and light , light is vibrating electrons vibrating at a rate/frequency that you can see with your eyes The same thing in a light bulb.

The resistance of tungsten wire to the to the vibrating electrons causes more friction and this makes heat and light.

Electricity , is in fact vibrating electrons.

The different rates of vibration convey different information. Type of information are in fact , heat or light. Radio or Television or Etc,.