first is a Jinja filter that can be used to return the first element in a list. Take for example the following.

{% set fruits=['banana','grapes','apples','pineapples'] %}

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Original List: 
{{ fruits }}

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First Element in List:
{{ fruits | first }}

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First Element in Sorted List: 
{{ fruits | sort | first }}

Something like this should be returned.

Original List: ['banana', 'grapes', 'apples', 'pineapples']

First Element in List: banana

First Element in Sorted List: apples