Multiple Regression Query

Hi, I'm an undergraduate psych student and have conducted a multiple regression for an assignment. This might seem like a simple question, but am a bit confused!
I've conducted a multiple regression with 3 predictors. Using the enter method the model is significant, however when looking at each individual predictor, none of the predictors are significant.
I have spoke to my tutors about this but am still left confused. They have suggested that the combination of the 3 predictors can produce a significant model but then individually they do not significantly predict the criterion. So how do i explain this in my write up of my study? I understand that none of my predictors are significant and therefore none of them predict the criterion but what does a significant model mean? can anyone explain this to me in simple terms!