what is the difference between [-3] and - 3?

Question

Very confused on this don't really know how to answer just need some help

Answer 1

If it is just a normal bracket such as (-3) then the value is simply -3
If you are using [ ] to represent absolute value, you should use |...|
an |-3| = 3
|'anything'| is the positive value of 'anything'

Answer 2

Thank you so much!