In a hand of poker that has 5 different cards that do not form any kind of match, the highest card is the high card and it is only useful against another hand of 5 unmatched cards if a showdown takes place.
When both players have the same High Card, they will compare the next highest card and so on until a winner is declared.
With the Ace being the highest ranking card, Ace-High would take down the pot at showdown if no player has at least a pair in their hand. If no player has an Ace, then King-High will win, then Queen-High, and so on. Ace-High is rarely the winning hand at showdown in a multi-way pot.
EXAMPLE “You got lucky there on the river, I thought my Ace high was good.”