Is the literal translation of the phrase הכנסת כלה, 'bringing in the bride'?
If this is correct, where are we bringing her in from, by whom and for what?
It is from the Hifil of the verb כנס and has different meanings depending upon where it is used.
In this context, it means to lead the Kallah as escorts, like is used in Shemot Rabbah 20:14 which says:
כָּךְ אָמַר הַקָּדוֹשׁ בָּרוּךְ הוּא אִם אֲנִי מַכְנִיסָן עַכְשָׁיו לָאָרֶץ אֵין בָּהּ חֵלֶק לִשְׁנֵים עָשָׂר שְׁבָטִים
According to the Shach (YD 360:1) the main הכנסת כלה, 'bringing in the bride', is bringing in the bride to the "chuppah"; accompanying the bride as she is led to the wedding ceremony.
Rashi (Sukkah 49b, s.v. Hotzo'as) extends הכנסת כלה, to providing financial support to needy brides, so that they can enter marriage in a dignified manner.