To calculate: The simplified form of expression |−3y|.

Formula used:
Property of Absolute Value:
Absolute value of product of two number is equal to product of absolute
values of those two number.
|p*q|=|p|*|q|
Where p and q are real numbers.
Absolute value of a negative number is equal to the opposite of that number.
|-p|=|p|
Where p is real numbers.
Calculation:
The absolute value of x, denoted |x|, is defined as follows,
When x is nonnegative, the absolute value of x is x and when x is negative, the absolute value of x is the opposite of x.
Now,
Using the property of Absolute value,
|ab|=|a|*|b|
The absolute value of a product is the product of the absolute values.
Therefore,
${\displaystyle \left|\frac{-3}{y}\right|=|-3|\cdot \left|\frac{1}{y}\right|}$
Apply the property of absolute value |-p|=|p|,
${\displaystyle |-3|\cdot \left|\frac{1}{y}\right|=3\cdot \left|\frac{1}{y}\right|}$
${\displaystyle =\frac{3}{\left|y\right|}}$
Hence, the absolute value of ${\displaystyle \left|\frac{-3}{y}\right|is\frac{3}{\left|y\right|}}$.