A function can be assigned to a struct and in this case we call it method.

Example:

type Person struct {
	Name string
	Age int
}

func (p Person) Speak() {
	fmt.Println("Hello from " + p.Name)
}

func main() {
	flavio := Person{Age: 39, Name: "Flavio"}
	flavio.Speak()
}

Methods can be declared to be pointer receiver or value receiver.

The above example shows a value receiver, it receives a copy of the struct instance.

This would be a pointer receiver that receives the pointer to the struct instance:

func (p *Person) Speak() {
	fmt.Println("Hello from " + p.Name)
}