I'm going to try to help explain this, but i'll be honest it feels like you're coming from a place of frustration. I'm sorry about that, take a break :)

(I'm not a language expert, but here goes)

var test int < bruh what? :=

These are the two forms of variable declaration and the second one is a declaration and initialization short hand. I most commonly use :=. For instance:

foo := 1 // it's an int!
var bar uint16 // variable will be assigned the zero value for unit16 which is unsurprisingly, 0.

func(u User) hi () { ... } Where is the return type and why calling this fct doesnt require passing the u parameter but rather u.hi().

This has no return type because it returns no values. It does not require passing u. It's a method on the User type, specifically u User is a method receiver. You might think of this akin to self or this variable in other languages. By convention it is a singke character of the type's name.

If that function returned a value it might look like:

func(u User) hi() string {
    return "hi!"
}

map := map[string] int {} < wtf

This is confusing because of how it's written. But the intent is to have a map (aka dictionary or hashmap) with string keys and int values. In your example it's initializd to have no entries, the {}. Let me rewrite this a different way:

ages := map[string]int{
    "Alice": 38,
    "Bob": 37,
}

Hope this helps. In all honesty, Go's language is very simple and actually rather clear. There's definitely some funny bits, but these aren't it. Take a break, come back to it later. It's hard to learn if you are frustrated.

I also recommend doing the Tour of Go here. My engineers who found Go intimidating found it very accessible and helped them get through the learning code (as there is with any language).

Good luck (I'm on mobile and didn't check my syntax, hopefully my code works 😎)