How Physics.IgnoreCollision works?

Even at Unity - Scripting API: Physics.IgnoreCollision I couldnt find the answer to my “point of view” of this question. When I use Physics.IgnoreCollision, that means my object A will pass through my Object B and it will collide if it finds another Object C on its way? or This IgnoreCollision means that it will ignore a call to “OnCollisionEnter”, “OnCollisionStay” and so on?

The doc you linked is pretty clear:

Makes the collision detection system ignore all collisions between collider1 and collider2.

If the two colliders never collide, they will never trigger any collision events.

The function acts on any distinct pair of colliders. You can call it multiple times to ignore more pairs, or you can use layer-based collision detection to filter entire layers from ever touching.