Refers to items being within easy reach or located where you can get them quickly. Make sure to have your tools handy when working on the car.
Pro Tip 2/3
Non-Physical Help
The term doesn't just refer to physical objects but also to anything that can be convenient, like a piece of advice or a service. His tips were very handy for tackling complex math problems.
Pro Tip 3/3
Preparedness Implied
Implies a sense of preparation or anticipation for needs that may arise. She always has a first aid kit handy on her hikes.