What happens if I reset my settings on the phone?

If I do that, only my settings will be reset or? Because I'm afraid that then everything is gone. Would be nice if someone could enlighten me.

(by the way, have a Huawei, if that matters)

Only if there was no second menu that reset everything.

The mobile phone will be reset to the factory settings, preferably the most important things before copying on sd card.

I'm not sure whether I had understood the question correctly.

That's exactly what happens to the button but EVERYTHING is gone, it's just the way you bought it.