Okay kiddo, so workplace interventions are when grown-ups (like bosses and managers) try make their workplace a better and happier place for everyone to work in.
Just like how we fix our toys when they break, grown-ups try to fix problems at work that might be making people unhappy or unhealthy. These problems can be things like too much stress, not enough breaks, or even bullying from other people.
To fix these problems, the grown-ups might do things like have meetings to talk about the problems and figure out how to make things better. They might give people more breaks so they can rest and feel better. Or they might make rules to stop people from being mean to others, because being kind is important.
Overall, workplace interventions are all about trying to make work a better place for everyone, so we can all be happy and healthy while we're there.