This is the 3567th most frequent Spanish word.
intenso
Intense; strong or extreme in degree.
Here, 'intenso' is used to portray a strong and deep personality.
Ella tiene un carácter intenso que siempre destaca.
She has an intense character that always stands out.
In this instance, 'intensa' refers to the brightness level of the light.
La luz en la habitación era tan intensa que tuve que cerrar las cortinas.
The light in the room was so intense that I had to close the curtains.
In this sentence, 'intenso' describes the demanding and concentrated nature of the training session.