He's got that right. You can wiki some string like "memory latency timing" and learn more than we present here.
There is a sequence of steps which occur in discrete clock-cycles necessary to perform a memory operation or operations of various kinds.
These are all obviously measured in integer clock-cycles.
Column Access Strobe or tCAS -- generally, the first number, most significant in comparing memory timing specs.
Row Access Strobe or tRAS -- I believe this is the last of the four basic timing numbers.
tRP -- Row Pre-charge
tRCD -- RAS to CAS delay
I'm doing this from the top of my head, don't remember all the specifics or remember them incorrectly. And candidly, I can't remember if the last two items mentioned are either 2nd or 3rd respectively.
Generally, given the state of the technology and the simplest implications, the higher the speed, the looser (larger) the timings or latencies.
For some memory makes, you could look at their spec pages for two models of the same model lines but of different speeds. They could give you an indication as to where to start if you want to overclock your own RAM instead of buying that of higher speed. So if I see a set of DDR3-1600 with 9-9-9-24, I might be able to run them at DDR3-1866 and 10-10-10-30.
And I can only opine that following short-cuts like that will save you time to learn or apply even more specific information and doing integer arithmetic.
Just sayin' . . . . .
[and obviously, I personally need to just become more familiar with spec-profiles for the new DDR4 in a choice of speeds.]