Economics Homework Help

I’m trying to study for my Economics course and I need some help to understand this question.

Discussion Topic: “When the labour market is in equilibrium, it means that the number of jobs in the economy is equal to the number of people willing and able to work (the labour force). Why is then that there will always be unemployment in the economy, even when the labour market is in equilibrium (even when there is a job for everyone)?” Discuss