The grace of the Lord Jesus Christ, and the love of God, and the communion of the Holy Ghost, be with you all. Amen (2 Corinthians 13:14).
The most important meaning of the trinity is that God, in itself, is a community. A community that is only possible in an interaction. If God was just the Father, how would he be able to show love? If God was only the son, who would he share his love with? If God was just the Holy Spirit, who would he love? Through the Trinity, God, in the eternal community between Father, Son and Spirit, shows that He is love. He also invites us people to participate in this eternal fellowship.