A device that directs internet traffic between devices and the internet. Like a traffic controller for data.
Your home router allows your laptop, phone, and smart TV to all share one internet connection.
A physical router forwards traffic between networks. In cloud, basic routing is usually built into the virtual network (VPC/VNet/VCN) via route tables and an implicit virtual router. For hybrid connectivity and dynamic route exchange (BGP), providers use gateway/router services such as AWS Transit Gateway or Virtual Private Gateway, Azure Virtual Network Gateway, Google Cloud Router, and OCI DRG.