I think pre-diabetes used to be called “glucose intolerant” ie you’re not dealing with glucose as efficiently as you did. So, your blood sugar is running higher than the norm, but not so high that you’d be formally classed as diabetic. Its an early warning sign really that type 2 could be on the horizon.
In terms of advice, I’d say heed the warning and take action now eg healthy diet, exercise, lose weight etc. That way you reduce the strain on the body and hopefully it starts to use its own insulin more efficiently, thus delaying the onset of Type 2 diabetes.