Q. How true is it that if one dreams of the letter “טּ” (tet) at night when they’re sleeping, it’s really a good siman?
Thank you!

A. See question 1426 in regards to the validity and importance of dreams. Indeed the Talmud (Baba Kama 55a) teaches that it is a good (beautiful) sign for one to see the letter Tet in a dream. The Talmud explains that although there are many occasions where the letter Tet appears at the beginning a word with a negative connotation, since the very first time it is presented in the Torah is by the word Tov, that beginning represents the true essence of the letter. Ben Yehodaya (p. 125) adds that the numerical value of the word Yofe (as in siman yofe or a beautiful sign) is 95, equal to the gimatrya of the words Bachalom Tov.
Ben Yehodaya quoting Ginzei Yosef also adds, that at the end of days when the powers of tumah and impurity will disappear, the world will be compared to the letter Tet. Namely it will be enclosed and protected from all sides, leaving open, as with a secure door the top side, representing Hashem’s care and shelter to all of His Creation.
Horav Shlomo Miller Shlit”a added that Menachem Ben Saruq explains that the term “Vayeit” – and Moshe stretched out his hand over the sea” (Shemos 14: 27), is exceptional in that the root of that word is only on the letter Tet. Symbolically, all those portents and saving miracles, were also done with the strength of the letter Tet.

Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit’a