Parallel lines are lines that exist in the same plane and never cross. In order to not cross, their slopes must be the same.
The line given is in slope-intercept form
y = mx + b
Where m is the slope and b is the y-intercept. Therefore the slope of the line y = 5x - 5 is 5.
Any line with a slope of 5 will be parallel.
For example, y = 5x + 1