If you just need to power your phone and laptop, all you need is an adapter to plug it into the wall. A razor or electric toothbrush may work that way as well, you just want to know if your device is dual voltage.
If you need to use hair devices that operate on high heat you’re going to need a converter. You just need to know how many watts the device needs, and get a converter that supports materially higher wattage than that.
But if you’re using electronics that aren’t dual voltage you need a transformer. For travel you want the smallest one possible based on the wattage of your device — because 7 pounds works much better in checked luggage than 30 pounds or more!