"Here we go" is used when you are about to start doing something you need courage and skills for. If you and your friend are about to dive into the water you can say "Here we go" that means "Let`s do it, man. Let`s just do it". If you are about to start dwelling on your presentation after you`ve done some introduction you also say "Here we go" (Let`s start it off). At the same time, if your wife has started yelling at you without any special reason (or may be with:-)) and you don`t like it you say "Here we go" means "performance has started, what to expect) Hope this is helpful.

It means that "something is going to start". For instance, imagine that you're going on holiday and you're just in your car, ready to leave. You could say "here we go" and then turn on the engine and begin your journey. I'm not an English native speaker but I hope my explanation is clear enough. :)

"Here we go" means that something is beginning. For example, if you are leaving on a trip or on vacation, you could say "Here we go" as the car leaves the house. Another use for "Here we go" is to imply that something bad is about to happen. For example, if it looks like it is going to rain you could say "It looks like rain, here we go again!" Hope that helps.