Question about Transition rules in AnimBlueprint

I am studying AnimBlueprint for the past few days and i should say that i understand very little .

I am studying the “3rd person blueprint” starter asset’s animblueprint to see how it works .

My question is about the Transition Rule shown in the screen shot , when you click on the Transition rule between "Jump Loop " and " jump End " nodes in page 1 of the screen shot , Page 2 opens and shows the rule to enter this transition .

Question is what does that " NOT " node means in page 2 ? does it mean :

1- take the value of the bool " Is In Air ? " and if it is Not true , enter transition ? < but the value must be true , since the character is in air >
2- take the value of the bool " Is In Air ? " and turn it to false , then enter transition ?

note that the character is still in the middle of the jump when this is going to happen, so the bool " Is In Air ? " is true .
Can someone please explain where in my interpretation i am wrong ? Thanks .

The player is not in the air when it activates the transition. This is playing a landing animation when he’s not in the middle of the jump. First thing the character should do when jump is over? Land

Does that make sense? The transition is between falling and landing. JumpEnd holds I expect a landing animation.

Yes , it makes sense now , somehow i thought this takes place when the character is about to land ,i mean close to the ground , but still in the air . thanks.