I do not understand about "Execute Once" option

Hi, I trigger trello, but it seems send duplicated events
I see settings has “Execute Once” option, but do not understand it clearly. Could you have any document for this?

The option will not make any difference on a Trigger-Node, only for regular ones.

What it does is that if multiple items get sent into a node it does not execute once for every item it receives, it only executes once for the first one.

So if you send 10 items into a HTTP Request node and they have the numbers 0 to 9, it normally makes 10 request. For each request a different number would be used.
f you set that option, it would only make one request and it the number it would use would be the first one, so 0.