Intel is well known for its 'tick-tock' launch strategy, where advancements in manufacturing processes one year are followed by big changes to processor designs the next. The Broadwell family of chips introduced in 2014 was ostensibly a 'tick' that marks the move from 22nm to 14nm manufacturing processes (although it could be argued that the all-new Core M family was therefore both 'tick' and 'tock').
The current Skylake standard is a 'tock,' with an all-new microarchitecture but using the same 14nm process as Broadwell. Sure enough, there's a new line of Core M chips that are now making their way into 2-in-1s and notebooks.
This reduction in the size of the transistors that make up the processor results in chips requiring less energy to do their thing, and less energy used means longer battery life and less heat.
"Tick-tock" by itself is the onomatopoeia English speakers use for the sound a clock makes. Depending on the design of the clockwork, the mechanism moves back and forth in a regular rhythm, slowly driving the clock hands forward.
So it's a two-step process, "tick" then "tock". The author uses this as an image to relate to Intel's regular development cycle, with processes updated one year followed by processor designs the next year, repeating year after year.