Nodes can process multiple items.
For example, if you set the Trello node to Create-Card, and create an expression that sets Name using a property called name-input-value from the incoming data, the node creates a card for each item, always choosing the name-input-value of the current item.
For example, this input will create two cards. One named test1 the other one named test2:
[
{
name-input-value: "test1"
},
{
name-input-value: "test2"
}
]