Appare vestigium invokes a tracking spell that “materializes as a swirl of gold, which illuminates traces of recent magical activity.” (CG48).
References from the canon
New Scamander used the spell when searching for Tina Goldstein in Place Cachee. He is able to distinguish where a Kappa had been; where Tina had stood facing a Zouwu and even a vision of Tina (CG48).
Appare is from the Latin "apparet" meaning "it appears"; Vestigium is Latin meaning "trace".