A dynamic IP address is an IP address that changes over time. This is in contrast to a static IP address, which remains the same. There are a few different ways to check if you have a dynamic IP address.
One way to check is to simply restart your router. If your IP address changes after you restart your router, then you have a dynamic IP address. Another way to check is to use a website or service that will tell you your IP address. If your IP address changes when you use a different website or service, then you have a dynamic IP address.