I really need to know how is called to see video tutorials on youtube about how to do it.
If you know a platform where i can get them free, tell me.
Thank you!
I think you answered your own question. Do you see the highlights at the bottom of the pic?
Flat design
is a style of interface design emphasizing minimum use of stylistic elements that give the illusion of three dimensions (such as the use of drop shadows, gradients or textures) and is focused on a minimalist use of simple elements, typography and flat colors.
I will say 90% of all flat designs I’ve seen still give a 3D feel by use of colors and shadows and gradients 
There are tons of tutorials on YouTube it seems. So just look for Flat Design. Here is a quick one.
Flat design goes hand in hand with minimal copy (text) and this particular example want to show use of colorful call to action buttons.
Isometric.
Isometric projected shapes with a gradient colorways to create an urban landscape.
Start here >>>
Isometric City >>>