Yes, that's a sinusoidal function. Its close cousin is the sine function.
Its amplitude is the absolute value of -3, which comes out to 3.
Its period is 2π/b, where b is the coefficient of x. Here, 2π/b is 2π(2), or 4π. Drawing your first cycle of this cosine function, you'll begin at (0,-3) and end at (4π, -3).
There's also a phase shift to think about. It's -c/b, which here is -(-5)/2, or 5/2.
