From Sonic Retro
The Trick Action (トリックアクション Torikku Akushon) is a recurring technique in the Sonic the Hedgehog series that was first introduced in Sonic Advance 2. By inputting button commands in midair, the player can gain point bonuses and propel the player character in a given direction. In Sonic Rush and Sonic Rush Adventure, they build up your Tension Gauge as well.
Putting Tricks to Good Use: Gameplay Tips
In Sonic Rush and Sonic Rush Adventure, the + trick allows Sonic or Blaze to perform a double-jump of sorts, by which you can reach areas that are otherwise inaccessible. Likewise, the / + trick launches Sonic or Blaze forward in that direction, and, for Sonic, damages enemies. In addition, tricks can be chained together for higher and higher bonuses.