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

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