I want to go eat. I’m going to eat. I’m gonna eat. “Je vais” is a fascinating sentence structure in French which is often used to express a desire to do something. You can use it to talk about the future whether in the next second or any moment beyond. Sorry I got very grammar nerdy but fuck it sometimes it’s cool. Yes, you can substitutes “manger” for any verb you want or any action want. For example, I’m going to bed, I’m going to work, and I’m going could be said as, “Je vais au lit, Je vais au boulot, Je vais sortir” in that order. The “JE” has a “jhuh” sound almost like pronouncing the beginning of “junk”. “Vais” can be said as, “Vay/Vae/Vai” like way but with a “v”. “Manger” is pronounced as “Man-jay”. “Au” = o, “Lit” = Lee, “Boulot” = boo-low, “Sortir” = Sore-tear… There you go – Enjoy!!!