The new MacBook Pro comes with two or four external ports, depending on the model you pick. But those ports are only of one type: Thunderbolt 3, which is compatible with USB-C.
But you probably have devices that use USB-A, Thunderbolt 1, Thunderbolt 2, DisplayPort, HDMI, or something else. How do you connect these devices? With an adapter.
If you’re planning to buy a new MacBook Pro, make sure you set aside a considerable amount of cash for the adapters you need. Apple doesn’t include any in the box, except for a power adapter.