This is the 887th most frequent Russian word.
группу
The Russian word "группу" means "group" (accusative case, singular).
The word 'группу' here is the direct object of the verb 'записался на' (signed up for). It refers to a class or learning group.
Он записался на новую группу по изучению английского языка.
He signed up for a new group for learning English.
The word 'группу' represents a cluster or collection, in this case a group of trees. It's in the accusative case as the object of motion.
Мы гуляли через густую группу деревьев.
We walked through a dense cluster of trees.
Here 'группу' refers to a band or ensemble, showing another common use of the word in the context of music. It's also in the accusative case as the direct object of the action 'organized'.