In simple terms, think about Interface as the Skeleton or Blueprint for your class. It specifies the lists of all such methods that a class must implement.

Sample:

interface Coffee {
    public function makeAmericano();
    public function makeCappuccino();
    public function makeEspresso();
    public function makeFrappuccino();
    public function makeIcedCoffee();
    public function makeLatte();
}

class AllInOneCoffee implements Coffee {
    public function makeAmericano() {
        echo "Making Americano Coffee";
    }

    public function makeCappuccino() {
        echo "Making Cappuccino Coffee";
    }

    public function makeEspresso() {
        echo "Making Espresso Coffee";
    }

    public function makeFrappuccino() {
        echo "Making Frappuccino Coffee";
    }

    public function makeIcedCoffee() {
        echo "Making Iced Coffee";
    }

    public function makeLatte() {
        echo "Making Latte Coffee";
    }
}

$coffee = new AllInOneCoffee();
$coffee->makeAmericano();
$coffee->makeCappuccino();
$coffee->makeEspresso();
$coffee->makeFrappuccino();
$coffee->makeIcedCoffee();
$coffee->makeLatte();

Output:

Making Americano Coffee
Making Cappuccino Coffee
Making Espresso Coffee
Making Frappuccino Coffee
Making Iced Coffee
Making Latte Coffee