We see this in the difference between the letter ד' and ה'. The letter ד' is written דלת which is similar to the word ‘דלית-it doesn’t have,’ referring to Malchus without this greater revelation, like the poor man who is lacking. The letter ה' is shaped like the ד' but with the addition of a small ו' in the bottom left corner. This small ו' represents the additional flow of Light and Life-force from the ו'=6 Attributes of Ze’eir Anpin.
This is similar to what is written in the Zohar (II, 38b), “as long as it (Malchus) does not receive from the masculine aspect (Ze’eir Anpin) it is called a [‘נַעֲרָ -girl’ without the letter ה' , and when it receives the masculine aspect, it is called a ‘נַעֲרָ ה-girl’ with the letter ה'] ...” כ ְמוֹ ש ֶכ ָתו ב ב ַז ֹהַר: "עַד לֹא קַב ִּילַת ד ְ כַר כוּ' ".
In Parshas Ki Seitzei when discussing the laws involving an unmarried girl, it uses the word ‘נַעֲרָ ה-girl’ but in is written ‘נַעֲרָ ’ without the letter ה' at the end. When spelled like this it can be read ‘נַעֲר-boy,’ since a girl who never had relations is like a boy in the sense that, at the moment, she is not able to bear children, just as a boy cannot become pregnant. However, after the girl has relations, she is called ‘נַעֲרָ ה’ with a ה', representing that she now has the (immediate) ability to become pregnant. This ability is due to what she received from her first relations.
The reason this is connected to the letter ה' is similar to what was explained above: When Malchus, which is like ד', receives from the ו=six attributes of Ze’eir Anpin, it becomes a ה' , since that flow from Ze’eir Anpin becomes the small ו' in the bottom left corner of the ה'.
Since a woman/girl corresponds to Malchus and a man to Ze’eir Anpin, that is why before relations she is called ‘נַעֲרָ -girl’ without the letter ה', and after she has relations, she is called ‘נַעֲרָ ה-girl’ with the letter ה'.
(זֹהַ ר חֵלֶק ב ב ֹ א לח, ב: "כ ְתִּ יב (ת ֵצֵ א כב, כג) : "כ ִּי יִּהְ יֶה נַעֲרָ ה בְתו לָה ", "נַעֲ רָ " כ ְתִּ יב, מַאי טַעְמָא ? מִּש ו ם ד ְ כָל זְמָן ד ְ לָא קַב ִּילַת ד ְ כַר ,אִּתְ קְ רֵ י נַעַר ,מִּ ד ְ קַב ִּילַת ד ְ כַר ,אִּתְ קְ רֵ י נַעֲרָ ה ") .
Since the general rule is that, usually, a woman does not become pregnant from her first relations, only from the second time she has relations.
