There’s very little to understand.
A Black Hole has Mass, Spin, and Charge. We can work out all these three things from the way a BH interacts with other matter around it.
Once we know the Mass, we can find the radius of the Event Horizon, inside of which the escape velocity is greater than light speed - hence ‘Black Hole’. Light cannot escape from inside this radius, and, by default, neither can anything else.
Also, knowing the Mass, we can calculate the gravitational acceleration towards the BH from any distance - just like stars, or Planets etc., gravity of a BH is inversely proportional to distance squared, so the closer you get, the higher the gravity… however, a BH ‘effectively’ only has ‘down’ - it has no surface like a star, as the Event Horizon is not a surface, just where light cannot leave… the ‘inside’ of BH does not exist, it is just a region inside the radius of the Event Horizon.
By ‘down’, I mean that no matter how close you get to a BH’s centre, all the Mass is below you, and the distance is very small, which is why a BH’s gravity gets insanely high when you approach the centre.
If you have a 3 Solar mass star, and a 3 Solar mass BH, at 2 million km away from the centre of both, the gravity will be the same… they have the same Mass.
If a BH has spin, then we know it does not have a point singularity - you cannot rotate around a 1-dimesional point… how would you know you were rotating?
If a BH has charge, it will affect matter with same/opposite charges nearby.
Black Holes are simple. The simple solution to a BH is also to never get near one.