Forum:Majestic Star dragon?

Hi, I have a question about majestic star dragon. It says on the card:Once per turn, you can negate the effect(s) of 1 face-up monster your opponent controls until the End Phase. Also, if the negated effect can be activated, you can activate it once as this card's effect. What does it mean with "Also, if the negated effect can be activated, you can activate it once as this card's effect". Is it like if it negates a monsters effect wich have the effect that it's effects can't be negated, then majestic stardust gains all of it's effects. And if it simply just negates a monsters effect that does not have the effect that it's effects can't be negated, does it nor gain the monsters effects?