This is the 10790th most frequent Spanish word.
descansan
"(They) rest."
The verb 'descansan' is used in this sentence to describe an action (resting) performed by the subject (Ellos) after engaging in an activity (playing soccer).
Ellos descansan en el parque después de jugar fútbol.
They rest in the park after playing soccer.
Here, 'descansan' illustrates the habitual behavior of the subject (las aves) during a specific time of day (at sunset).
Las aves descansan en los árboles al atardecer.
The birds rest in the trees at sunset.
In this case, 'descansan' signifies a general or planned action (resting) associated with a particular period (vacation).