This is the 1913th most frequent Russian word.
присоединиться
"To join" or "to connect oneself."
In this sentence, 'присоединиться' is used to convey the action of joining or becoming a part of a group for collaborative purposes.
Я решил присоединиться к группе волонтёров.
I decided to join the volunteer group.
Here, 'присоединиться' emphasizes the desire to become part of an ongoing activity or interaction, in this case, a discussion.
Она хотела присоединиться к обсуждению, но ей помешали.
She wanted to join the discussion, but she was interrupted.
In this instance, 'присоединиться' indicates the act of joining others in their physical activity or endeavor, specifically traveling.