The thing is, you didn't understand? Or you don't want to understand? 'Half' is a big universe, be more specific on what you did not understand.
'Who enters the mud, wants to get dirty.' This is not a 9th grade problem, probably you are doing some kind of technical school, what is the course/subject that you are doing?
Look for RTL logic at google, you can do logic gates using relays and resistors.
Yes, you can disassemble a kitchen timer and build some sort of mechanical timer there.