No Gi classes is simply training Jiu Jitsu without the traditional uniform (gi, kimono, etc). Typicaly shorts, rash guards and spats are worn instead.
At a broad level, good Jiu Jitsu in theory and practice should work regardless of the circumstances: if you want to call yourself a high level grappler then it shouldn’t really matter what you or your opponent is wearing. The strong foundational base Heroes preaches, including the emphasis of thinking of every position or technique in order of body position first, then legs, then grips is designed to make the transition between gi and no gi game easier.
Realistically the changes in grip mentality does the no gi game feel different and takes some getting used to. One word to describe the No Gi game is slick: a match is often slippery and fast paced compared to a gi match.
From a competition standpoint the rules in No Gi are far less standardized than the Brazilian Jiu Jitsu gi rules, where the IBJJF rules are the de facto standard. No Gi competitions may or may not be Brazilian Jiu Jitsu based, and have rules that mindsets that accommodate other grappling styles as well. A good rule of thumb when competing without a gi (or with for that matter) is to be ready for anything.
Heroes encourages a ratio of about 80 percent “gi” training to 20 percent “no gi”. We have a strong belief that training with and without actually creates more well rounded, better prepared grapplers and martial artists.