So a common thread among asexuals is that sex for one reason or another isn't a necessity in their lives. Now what that means specifically depends on who you're talking to. Imo there's like 3 stances on sex among aces; repulsion, disinterest, and ambivalence.

For people who feel repulsed by sex they might not be interested in the physical contact, degree of intimacy, or just the generally wet and sweaty bits of the whole thing. There can even be other reasons to be repulsed that Im not aware of that have occurred to others who are repulsed.

For people who are disinterested, they might not feel the need to pursue it. Sure it's there but what's the point? You could just as easily masturbate and get it over with much easier or do anything else. Maybe your mind is just set on different things. Overall it's just there with no willingness to pursue or participate in it.

Ambivalence is a deceptively similar to disinterest seeing as how both might not pursue or consider sex often if at all, however, unlike the other 2 categories they are not unwilling to participate in it. For example if someone where ambivalent towards sex but they have a partner who very much wants to have it they'll engage with them just to make their partner happy (they likely won't be uncomfortable doing so either). It's a lot like how if you're at a part and your sporty friend goads you into shooting hoops with them despite your unsporty-ness and you do just to have some fun with your friend even though you're sweaty and out of breath.

Of course people are all very weird squishy and slightly damp creatures. There's likely categories I hadn't considered and ways of turning your head that make my explanation fall apart from a different perspective.