People from Spanish speaking countries say 'Hola!' when they meet someone.
'Hola' is similar to 'Hello' in English.
After saying listening 'Hola', the listener can respond - 'Hola!'
Note: In Spanish, the letter 'H' is not pronounced; therefore 'Hola' will sound as 'Ola.'
We can use either of the following to ask - How are you?
The former is the informal way, which one can use with his friends, colleagues, family members, etc. At the same time, the latter is the formal way, which is used when one meets someone of the first time, elders, etc.
¿Cómo estás? - Informal
¿Cómo está? - Formal
We can use any of the following to state to answer the earlier question.
Estoy bien - I am Good/Fine
Bien - Fine/Good
Muy Bien - Very Good
Suppose one wants to say 'Thankyou' in Spanish. You can say - Gracias.
You are Welcome in Spanish - De Nada / Por Nada