I recently saw by a Friday night dinner that the challah bread was dipped in salt a few times. Is there a specific amount of times to dip it, and why dip it in the first place?
Great question. I myself have had this question and looked it up, and I found the article Why Do We Dip the Challah Bread in Salt? to be very interesting.
To sum up what's written there:
It's dipped in salt every time bread is eaten, and not only on Shabbos. The reason is that your table is compared to an altar, and since sacrifices brought on the altar all had salt, so too your bread should.
Based on Kabbalah, it is done because bread represents divine kindness, whereas salt represents strict divine judgment. And, we want kindness to overpower strict judgment.
It is done three times because, again based on Kabbalah, bread (לחם in Hebrew) has the numerical value of 78, the name of G-d (י-הוה in Hebrew) has the value of 26, and 26 x 3 = 78 (26 is the value of G-d’s name, and 3 is the 3 times we dip). This reminds us that we don't only live from the bread we eat; but, also the blessing of G-d in our food.
Shulchan Aruch Harav 167:8
...If the bread is made from fine flour, it is flavored with spices or with salt as our bread is, or the person desires to eat plain bread,he need not wait for [salt or relish]. If, however, he desires to wait, he has license to do so. He need not be concerned with the interruption made between washing and reciting the blessing HaMotzi, since [he is waiting for something] necessary for the meal, even if it is not necessary for the blessing HaMotzi.
Nevertheless, it is customary to place salt on the table [before the recitation of the blessing HaMotzi, even when the bread does not require it. The rationale is that] the table is comparable to the altar [of the Beis HaMikdash] and our food, to a sacrifice, and it is written: “On all your sacrifices offer salt.” [Moreover,] when Jews sit at the table and wait for each other to wash their hands, they are [idle], without mitzvos. [Hence,] the Satan makes accusations against them and the “covenant of salt” protects them. Therefore, it is a mitzvah to place it on the table even if one does not partake of it. According to Kabbalah, one should dip the piece of bread [over which the blessing HaMotzi was recited] in salt three times....
The Babylonian Talmud, Berakhot 40a, says that a host should not serve a meal until salt or relish has been laid on the table and for health reasons.
Isaac ben Solomon Luria, known as Ari, wrote that G-d is composed of ten parts, called Sefirot. He had the mystical view that when you dipped the bread in salt three times it was symbolically joining the parts of G-d. He saw that the Hebrew word for bread, lechem (l-ch-m), shares the same letters of the Hebrew word for salt, melach (m-l-ch), though in a different order.
Moses Isserles, or Ramah, who lived after the Ari, rationalized the dipping of bread on kosher salt. He wrote that:
“It is a mitzvah to set salt on the table before breaking bread because the table is like the [Temple] altar and food like a sacrifice.... And it is a shield from demons.”