。
The train passed us.
Literal
Train [subject-が] we [of-の] side [object-を] passed-through.
通り過ぎる ('to pass by, go past') is a compound verb: 通る (pass through) + 過ぎる (exceed, go beyond). Together: 'pass all the way past.' 側 (そば, 'side, vicinity') + を + verb of motion is the standard way to mark the route — 'went past (our) side.'