Hola todos

Hola-Hello
Todos- Everyone

Buenos Días - Good Morning ( greeting someone)
Buenos Tardes - Good Afternoon/ Good evening ( greeting someone)
Buenos Noches - Good night

Buenos Noches is used before going to sleep
If you are greeting your senior / teacher at night(call)
You will say
Buenos Tardes Profesor/ Profesora
Lo siento, estoy llamando tan tarde
( Sorry , I am calling up so late)
¿Puedo hablar con usted ahora?
(Can I talk to you now?)
Yo tengo una duda( I have a doubt)

When you want to ask someone's name
Cuando tú quieres / usted quiere preguntar el nombre de alguien

Hola
¿Cómo usted se llama? o ¿cómo tú te llamas? ( What is your name?)

Aquí, va a responder
Here, you are going to respond-

Me llamo "tu nombre"
(My name is "your name")

Tú y Usted
Both of them mean "you"
Tú is Informal
When you are talking to your friends or close ones or cousins
It can also be used when you are talking on a friendly note with the teacher or someone
Usted is Formal
When you are talking to elder people or your teacher, or in the office

Yo -I
Tú - You
El/ Ella/ Usted - He/She/You
Nosotros -We
Vosotros - You all
Ellos/Ellas/Ustedes- They / You all

. Masculino Femenino

This Este Esta
That Ese Esa

This -Esto -neutral
That- Eso - neutral