In order to make the attack, Vegeta draws his hands back, gathering all of his Ki, and thrusts his palms forward, discharging a massive beam of energy towards his opponent. Vegeta uses a similar attack against Recoome called Final Crash.
It is not until Vegeta uses this move during his fight with Perfect Cell that he dubs the attack the Final Flash. Though Cell was significantly more powerful, the sheer amount of energy that Vegeta put into the attack, reflected by significant charge time, nearly obliterated the overconfident Cell as well as the entire Earth. If Vegeta had not directed the blast upwards to avoid damaging the Earth, Cell would have been completely destroyed. Sensing the danger only at the last second, Cell attempted to dodge the beam as the destructive energy disintegrated the ground on which he stood and continued off into deep space. When the dust cleared, Cell had lost half of his upper torso. Despite this, and to Vegeta's surprise, Cell was able to regenerate himself and continue the fight.
In the anime (but not in the manga), Vegeta uses this move against the Cell Jr. he is fighting against, but the attack is easily dispatched. In this instance, Vegeta spent only a few seconds charging up the attack rather than the several minutes used in its debut (presumably due to the desperate situation at hand) which could explain why the Cell Jr. was able to effortlessly deflect an attack that Perfect Cell himself was previously vulnerable to. He later uses it against Goku as Majin Vegeta (the attack name is heard, but not seen, as he placed the fingers of his hands upward instead of the heels of his hands to each other) and then later against a swarm of Buus while buying time for Goku to charge his Spirit Bomb.
It should be noted that in the anime, the attack's color matches Vegeta's default aura (but this is not true in the Playdia Game "DBZ Gaiden" where (Super Saiyan) Vegeta Shoots a Blue Final Flash. Vegito also combines this move to make the Final Kamehameha.This move is often seen in Vegeta's repertoire in the Dragon Ball Z video games, often as one of his strongest attacks, if not the very strongest. It also comes in a blue color like the Kamehameha in Final Bout.