You may want to read OSI 7 layers model. Those L1,L2,L3,L4 and L7 concept derived from that model. L1 is the physical access. It is the cable, the fiber or the WiFi itself. L2 is datalink. We use Ethernet for IP network. The device that mainly handle communication at this later called a switch. L3 is network. In IP Network it handles the routings between IP Network. The device usually called as a router.

Some devices can do L2 and L3 at the same time. That’s why another term came up: L2 only switch.

And so on, you can read it more on [1].

1] https://en.m.wikipedia.org/wiki/OSI_model