Answer:
This means it has high amounts/alot of mass.
Explanation:
If things with mass attract each other, and things that attract strongly have a high gravity, then we can make the conclusion things with high mass have a high gravitational pull, and vice versa.
The question tells us Black Holes have great(high) gravity, so we can say Black holes also have high mass.
If this is confusing say so, and I'll try to elaborate.
