Efraim Palvanov on his website "Mayim Achronim: Uncovering the depths of Torah wisdom" (article: Secrets of the Five Special Sofit Letters) explains that in Parasha Behaalotecha Moshe Rabbeinu was for the first time "stumped" by a question an had to ask G-d what to do in the particular situation:
The son of the Israelite woman pronounced the Name in blasphemy, and he was brought to Moses—now his mother’s name was Shelomith daughter of Dibri of the tribe of Dan—
and he was placed in custody, until the decision of יהוה should be made clear to them.
Why was he placed in custody until the decision of G-d? The Sifra (Emor, section 14:5) on this pasuk explains that they did not know if the person was liable or not:
they did not know whether he was liable to the death penalty or not.
The second one was Pesach Sheni, third was the wood-gatherer, fourth was the case of Zimri and Kozbi and the fifth one was the case with the daughters of Tzelofchad.
The Shelah (Shenei Luchot HaBerit, Torah Shebikhtav, Eikev, Torah Ohr 30) explains something interesting, Moshe Rabbeinu permitted himself to say about himself "And any matter that is too difficult for you, you shall bring to me and I will hear it.”- Devarim 1:17. G-ds reaction to this was "that he could not even deal with a problem that women knew the answer to, i.e. the problem presented by the daughters of Tzlofchod". I think this is a really important lesson that G-d wants to teach us, that we always need to be humble. We cannot say that "I have a bigger claim to the Torah than you!", since the Torah was given in the dessert, we must humble ourselves and say that everyone has an equal share in the Torah (Bamidbar Rabbah 19:26).
Explains Efraim Palvanov:
These five questions (mekoshesh, nokev, tzelofchad, pesach sheni, kozbi) correspond to the five special Hebrew letters that have a distinct symbol when they appear at the end of a word: The “open” mem (מ) becomes a “closed” mem sofit (ם) while the “bent” nun (נ) becomes a “straight” nun sofit (ן), just as the “bent” tzadi (צ) becomes a “straight” tzadi sofit (ץ). The “coiled” pei (פ) and khaf (כ) unravel into the straight pei sofit (ף) and khaf sofit (ך). Together, these five unique letters are referred to by the acronym מנצפ״ך, “mantzepach”, and carry a tremendous amount of meaning. What is the origin and purpose of these special letters?
He goes further to explain the connection between these fiver matters/words and the concept of Gevurah. See here.
The Pirkei DeRabbi Eliezer (48:17) goes to explain that the five letters of the Torah (Mantzepach) are a reference to the future redemption:
The five letters of the Torah, which alone of all the letters in the Torah are of double (shape), all appertain to the mystery of the Redemption.
See also Bereshis Rabbah 1:11:
R. Simon said in the name of R. Joshua b. Levi: Manzapak [מנצפ"ך] is a Mosaic halahhah from Sinai. R, Jeremiah said in the name of R. Hiyya b. Abba: They are what the zofim [i.e. prophets] instituted. It once happened on a stormy day that the Sages did not attend the House of Assembly [i.e. the Academy]. Some children were there and they said, 'Come and let us make a House of Assembly. Why are there written [two different forms when the following letters come in the middle or end of a word respectively] mem [מ] mem [ם], nun [נ] nun [ן], tzadi [צ], tzadi [ץ], pai [פ] pai [ף]? It teaches [that the Torah was transmitted] from utterance [מאמר] to utterance, from Faithful [נאמן] to faithful, from Righteous [צדיק] to righteous, from mouth [פה] to mouth, and from hand [כף] to hand. From utterance to utterance — from the utterance of the Holy One, blessed be He, to the utterance of Moses. From Faithful to faithful— from theAlmighty, who is designated, "God, faithful King," to Moses, who is designated faithful, as it is written, "He [Moses] is faithful in all My house" (Numbers 12:7). From Righteous to righteous— from God, who is designated righteous, as it is written, "The Lord is righteous in all His ways" (Psalms 145:17), to Moses who is designated righteous, as it is written, "He executed the righteousness of the Lord" (Deuteronomy 33:21). From mouth to mouth — from the mouth of the Holy One, blessed be He, to the mouth of Moses. From hand to hand: from the hand of the Holy One, blessed be He, to the hand of Moses. They completed them and they grew to be great sages in Israel; some say that they were R. Eliezer, R. Joshua and R. Akiba. They applied to them the verse, "Even a child is known by his doings, etc." (Proverbs 20:11).