They're abstract. They're "dissociated" or whatever. But, you can imagine them how you like. FWIW.
Like, if you dislike a mechanic that touches on hp, you can imagine it in a way you find distasteful, and demand it be excised from the game.
The 12th level 5 fighter has his 2nd Extra Attack (since 11th) and can hit 3 times per round. He probably doesn't do a standard-issue 5e Ogre's 59 hp in one hit, it might take 2 or all three, IDK, there's no assumption of magic items or feats, so there's a range of possibilities....
In 5e you can move-attack-move-attack some more - everyone can, from 1st level, even.
5th, 11th, and 17th IIRC.
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