Sheryl Lee Ralph and her son Etienne Maurice are offering solid advice to fire-affected families ... emphasizing that not everyone in L.A. is wealthy, and victims need all the help they can get.

The duo spoke to TMZ Monday while volunteering at Etienne’s WalkGood Yard, his nonprofit wellness studio ... where Sheryl pointed out regular working-class folks have lost everything too, and donations are needed to assist anyone who's been affected.

Speaking from her own prior experience with a house fire, Sheryl urged those struggling after losing their homes to hold on and not lose hope, saying things have to get better.

Sheryl added a reality check, saying fires could rage for another week, and for some families it might take years to rebuild their lives.

Other celebs are also jumping in to volunteer and donate, including Beyoncé, Paris Hilton, Angelina Jolie, and more.