“There were no greater festivals for Israel than the 15th of Av and Yom Kippur.” (Gemara Taanis 26b)
Just like Yom Kippur, Tu B’Av was a day of forgiveness, when the generation that came out of Egypt stopped dying in the desert and Hashem forgave the Jewish people for the sin of the spies. On this day, certain restrictions on marriage were lifted. Also, the guards preventing Jews living in the kingdom of Yisrael from travelling to the Beis Hamikdash in Yehuda were removed. Rabbi Nivin says that Tu B’Av is a day of unity: between the Jewish people and Hashem and among each other.
In honor of Tu B’Av I wrote an article on matchmaking in Los Angeles. You can read it online here.
Have a wonderful Shabbos!