If you want to connect multiple computers to a DSL line, you will need a router.
An Ethernet router connects computers using Ethernet cables:
Each computer that needs to connect to the DSL service will need an Ethernet cable. And then you will need one more Ethernet cable to connect the router to your DSL modem (this Ethernet cable comes with the DSL kit).
Wireless routers can connect some computers using an Ethernet cable (typically, up to 4 computers), and many more computers using the wireless antenna:
You will need at least one Ethernet cable to connect the router to the DSL modem.