An "ace" (a shortened term for asexual) is someone who has little or no sexual attraction or sexual desire, and, like queerness, it covers a wide and colorful spectrum. "Gray" asexuals find themselves swimming in the gray areas of sexual desire and dip their toes into both sides of the sexual pool.

: to earn a high grade on (something, such as an examination) especially : to get an A on. b. : to perform extremely well in. he aced every subject.

She is into you. It is self-explanatory. “Ace is a card which is the superior highest ranked”, meaning you are the most super, and rank the highest, i.e. Number 1 in her heart.

ace (n.) c. 1300, "one at dice," from Old French as "one at dice" (12c.), from Latin as "a unit, one, a whole, unity;" also the name of a small Roman coin (originally a rectangular bronze plaque weighing one pound, it eventually was reduced by depreciation to half an ounce; in imperial times it became a round coin).