Access modifier

public: Allows access to methods and variables from outside the class.
private: Restricts access to only within the class where it is defined.
protected: Provides access within the class it is defined and its subclasses (derived classes).
get: Defines a getter method for private properties.
set: Defines a setter method for private properties.

=> If no access modifier is specified, the default is public.

Example

class Car {
	public start:string;
	private sheet: number;
	protected shape: string;

	constructor(str: string){
		this.start = str;
		this.sheet = 5;
		this.shape = "circle";
	}

	public getSheet(){
		return this.sheet;
	}

}

class Car7Sheet extends Car {
	constructor(){
		super("7 sheet start");
	}

	public getShape(){
		return this.shape;
	}
}

const svCar = new Car7Sheet();
console.log(svCar.getShape()); 
// "circle"
console.log(svCar.start);
// "7 sheet start"

Example of getter and setter

class Person {
    private _age: number;
    private _firstName: string;
    private _lastName: string;

	constructor(age: number, firstName: string, lastName: string){
		this._age = age;
		this._firstName = firstName;
		this._lastName = lastName;
	}

 
    public get age() {
        return this._age;
    }

    public set age(theAge: number) {
        if (theAge <= 0 || theAge >= 200) {
            throw new Error('The age is invalid');
        }
        this._age = theAge;
    }

    public getFullName(): string {
        return `${this._firstName} ${this._lastName}`;
    }
}

const person = new Person(24,"dang","khanh");
person.age = 12;
console.log(person.age);
// 12
person.age = -1;
// "Executed JavaScript Failed:"
// The age is invalid
console.log(person.age)

References

Typescript getters-setters