SIGNALS YOU WILL SEE BEING USED
For the basic signals for riding in a group take a look at this – https://www.cyclingweekly.com/videos/fitness/group-riding-how-to-use-hand-signals-video
CALLS YOU WILL HEAR
If you hear a call of “CAR UP” it means that a car is approaching the group from BEHIND
If you hear a call of “CAR DOWN” it means tht you are being warned of a vehicle approaching the group from AHEAD