What happens if you activate a card effect that returns two of your monsters and one own to the hands but opponent only has monster on field in Yu-Gi-Oh?

In this scenario, the card effect will still resolve as intended, even though your opponent only has one monster on the field. Here's why:

* Card Effects are Absolute: Card effects work as written regardless of the situation on the field. They don't care about the opponent's monster count.

* Targeting: The effect likely doesn't specifically target an opponent's monster. If it did, you wouldn't be able to activate it without a target.

* Chain Resolution: The effect will activate, and you will choose two of your monsters and one of your own to return to your hand.

* Opponent's Monster: The opponent's monster will remain on the field, unaffected by your card's effect.

Example:

Imagine a card that reads: "Return 2 of your monsters and 1 of your own to your hand."

If you activate this effect and your opponent has one monster on the field, the following will happen:

1. You choose two of your monsters and one of your own to return to your hand.

2. Your chosen monsters are sent back to your hand.

3. Your opponent's monster remains on the field.

In summary, your card's effect will still activate and resolve according to its text, even if your opponent's field doesn't have the required number of monsters.