The Tabernacle proper and the furniture described in Exodus 25 symbolize the presence of God among his people. The curtains in chapter 26 indicate the restricted access to God’s presence. They set up barriers to the symbols of God’s presence, and later laws would restrict who could pass those barriers and at what times.
The bronze altar (27:1-8) sat in the tabernacle courtyard. It demonstrated to the people that there could be no access to God without a substitutionary sacrifice.