Question

What do these symbols mean, give me examples and the meaning of these lines? ---> |-3|

Answer 1

Those lines mean absolute value. A real number x is the non-negative value of x without regard to its sign.
For example, the absolute value of 3 is 3, and the absolute value of −3 is also 3. The absolute value of a number may be thought of as its distance from zero.

Answer 2

http://www.purplemath.com/modules/absolute.htm

Answer 3

Thanks :)