This is the 8916th most frequent Spanish word.
tranquilo
Calm; quiet; peaceful.
The word 'tranquilo' in this context is used to denote a sense of personal calmness or peace.
Estoy tranquilo después de meditar.
I am calm after meditating.
Here, 'tranquilo' describes the peaceful and quiet nature of a location.
El lugar es muy tranquilo en las tardes.
The place is very quiet in the afternoons.
In this instance, 'tranquilo' is used as an interjection to urge someone to remain calm.