a timmer ?

Hello everyone, i want to have in my program something that will count some random amount of time for example between 10 and 20 minutes and once this time is over to stop the curent flow of the program and execute some other lines of code, is that possible ? is there any library for that ? I am not asking the code just some baselines
Also a widget-like clock that will start and stop with specific comands would be useful

Thanks in advance