Overwatch is not released yet. However, the developers are already showcasing Tracer. Moreover, she will arrive into Heroes of the Strom earlier than you can play her in Overwatch. Starting April 19, the hero will be available to those who have pre-purchased a digital copy of Overwatch: Origins Edition. For everyone else, the hero will be released on April 26.
Here is an In Development video about the hero. You can see different Tracer skins as well as animations and spells.