The arrows are pointing to the optimal VSA entry area. Usually it is preferred to use the 5 or 15 minute to pinpoint the entry, which would be in the vicinity the apex of the wave (annotated with corresponding arrows). In real time you would just drop down to the 5/15 and wait for the signal.
The goal in practice and while backtesting is to learn how to identify this spot. Yes, its learnable. As a matter of fact i think most people cold have it fairly well understood in 3-6 months but will you have the discipline and emotions under control at that point? Thats the hard part. This is actually the easy part IMO.
Sources of education:
Tom Williams spread analysis VSA / Master the Markets
Pete Faders VSA*
Read the ticker dot com
Avoid buying into weakness/supply/resistance
Avoid selling into strength/demand/support
Avoid entry when price is in middle of a range (phase B)