Use counters to keep track of time for flashing lights and warning bell signals?

Can anyone explain what this means? A few practical examples can help..

 

Counter - something that counts. You have some timing pulses (ticks), and when you reach the right amount of ticks, you do something.

Another approach to your train problem is a monostable timer, like http://www.technologystudent.com/elec1/5554.htm