This is the 2974th most frequent Polish word.
odbywały
"Odbywały" means "they took place" or "they occurred" in English.
In this sentence, 'odbywały' is used to indicate past continuous action, describing that events (meetings) were happening on a regular basis.
Spotkania odbywały się co tydzień w sali konferencyjnej.
The meetings took place every week in the conference room.
Here, 'odbywały' describes past recurring actions, specifically the timing of scheduled events (lessons).
Lekcje odbywały się po południu.
The lessons were held in the afternoon.
This usage of 'odbywały' highlights past actions contingent on specific conditions, that is, exercises occurring outdoors depending on the weather.