This is the 4320th most frequent Russian word.
бегут
"Бегут" means "they run."
The word 'бегут' is the third-person plural form of the verb 'бежать' (to run) used to indicate the action of running performed by multiple subjects (the children) in the present tense.
Дети бегут к реке, чтобы играть в воде.
The children are running to the river to play in the water.
In this usage, 'бегут' metaphorically describes the movement of clouds, giving a poetic sense of their swift motion.
Тучи бегут по небу, предвещая дождь.
The clouds are rushing across the sky, foreshadowing rain.
Here, 'бегут' expresses the action of running performed by multiple subjects (the soldiers) and highlights urgency within the context.