In general, pocket kings (also known as "K-K") are a strong starting hand in Texas hold'em and are considered one of the best pairs a player can have. However, like all hands in poker, the strength of pocket kings can change depending on the specific situation and the board.
If you see an ace on the flop, it's important to consider your position, the size of the pot, the betting patterns of your opponents, and any other factors that might affect your decision. If the ace on the flop gives your opponent a higher pair or a potential straight or flush, it may be a good idea to fold your pocket kings to avoid losing a large amount of chips.
On the other hand, if the ace on the flop doesn't seem to improve your opponent's hand, you may want to consider continuing to play and betting to try to win the pot. It's always important to pay attention to the board and use your best judgment when deciding how to play your hand.
In general, it's a good idea to be cautious with pocket kings and consider folding if the board is unfavorable or if there are strong betting patterns indicating that your opponent has a strong hand. However, pocket kings can still be a strong hand in many situations, and you should always consider your options carefully before making a decision.