It's the present participle of the verb "relajarse" (to relax), which is a gerund form used to indicate an ongoing action.
Here are some examples of how to use "relajándose":
* Ella está relajándose en la playa. (She is relaxing on the beach.)
* Los niños se están relajando en el jardín. (The children are relaxing in the garden.)
* Me gusta relajarme con un buen libro. (I like to relax with a good book.)
Let me know if you have any other Spanish words or phrases you'd like to know the meaning of! 😊