Understanding Voltage and Current.
An analogy with water in pipes is often helpful in understanding the basics of electricity.
Voltage is like water pressure. It is a force. If the force is too strong your pipes will burst. Too low and your shower may not work at all.
Current is like flow-rate. Litres per second or how fast your bath fills. It depends on how big your supply pipes are. If your water supply has a low flow rate, you won't be able to fill your swimming pool in 10 minutes. If your water supply can fill your pool in 10 minutes, you can still use it to connect a drip-watering system for your pot-plants that only draws a cupfull a day of water.
Voltage
If the laptop requires 19V you should use an power-supply that provides the same voltage. If the power supply voltage is significantly more, it will damage your device and could start a fire. If the voltage is less, the device will not work, actual damage is less likely.
Current (Amps)
If the laptop need to draw 4.7A, your should use a power supply that is capable of providing At least that number of Amps. More is ok. Less means the device will probably not operate correctly.
Further information
See Choosing power supply, how to get the voltage and current ratings?