First, lets write the equation y+1=-3(x+2) in "slope-intercept" form

y+1=-3(x+2)

y = -3x - 6 - 1

y = -3x - 7

has slope m1 = -3

let y = m2 x + b, where m2 is the slope and b gives the y-intercept

be the equation of a line that is perpendicular to the line with the equation y+1=-3(x+2) thus

m2*m1 = -1 since the lines are perpendicular

m2 = -1/m1

m2 = -1/(-3)

m2 = 1/3

y = x/3 + b

now the only thing left to find is b

since y = x/3 + b passes through the point (0,-5) we have

-5 = 0/3 + b

b = -5

the equation of the line that we are looking for is

y = x/3 - 5.