Hi, I’ve been learning some services from the documentation and I came across this one (now on my list) but I don’t understand its use or utility (I don’t fully understand it) and I didn’t find an example script to clarify it.
Someone would be so kind to clarify what is its use and how to use it correctly, I would appreciate it very much! 
local PhysicsService = game:GetService("PhysicsService")
-- Next steps...
Its just for the use of CollisionGroups
which allow for certain parts to not collide and some to collide without affecting the CanCollide property.
I would suggest searching online since it has a lot of results for Collision Groups
Oh I see! So if I want to learn it, should I focus on learning its functions?
Yea, its only useful in certain situations.
I don’t really use it that much as you can set the CollisionGroup just by going to your
Model>Advaced>Collision Groups
Then you can add collision groups by name and you can assign parts to a collision group by clicking on the part then clicking on the plus button of the collision group.