God's overarching command to build the Mishkan is Shemot 25:8:
וְעָשׂוּ לִי מִקְדָּשׁ וְשָׁכַנְתִּי בְּתוֹכָם
And they shall make Me a sanctuary and I will dwell in their midst.
R' Samson Raphael Hirsch, in his commentary1 on this verse, explains that its two clauses present two intertwined purposes for this construct, each alluded two by one of our names for it:
"And they shall make me a sanctuary" - a "Mikdash" - requires us to set aside space and materials in a prescribed manner for God's service, symbolizing "giving up the whole of our private and public life to the fulfillment of the Torah."
"And I will dwell in their midst" refers to God's responding to our sanctifiation by dwelling - "Mishkan" - amongst us, putting "the protecting and blessing-giving presence of God in our midst, manifesting itself in the happiness of our private and national lives."
So that the sphere within which we have to try and find the meaning of the Tabernacle as a whole, and its component parts in detail, is simply mutual covenant-relationship between God and Israel, brought about by the giving and acceptace of the Torah.
R' Hirsch's commentary goes on to explore the symbolism of every material and technique used in constructing the Mishkan, every component and vessel contained in it, and, elsewhere in the Torah, every service performed in it - all fleshing out details of and variations on this basic dual theme of our dedication to God and His kindness to us. If you want to learn more about elegant, edifying significance to be found in every detail of the Mishkan and the service therein, I highly recommend study of R' Hirsch's commentary on the rest of Shemot 25 - 30 and then on the passages in Vayikra and elsewhere that describe the various services.
1. Quotations below are taken from an earlier English translation, the one I have on hand.