Energy has negative and positive signage, so is it a vector?

No, it is a scalar. Force is an example of a vector. This is why we draw free-body diagrams and represent forces as arrows. Torque is another, being the rotational analogue of linear Force.

Linear force is defined as #vecF = mveca#, in #N#.
where #m# is the mass and #veca# is the linear acceleration.

Torque is defined as #tau = vecr xx vecF_(_|_)#, in #N*m#
where #vecr# is the lever arm distance, and #vecF_(_|_)# is the perpendicular force that causes the rotation.

On the other hand, some of the Energy functions that you encounter in a typical physics class are:

Linear Kinetic Energy:

#K_L = 1/2 mv_L^2#
with #m# for the mass and #v# for linear speed (not velocity).

Rotational Kinetic Energy:

#K_R = 1/2 Ivecomega^2#
with #I = Cmr^2# (#C# depends on the object), #m# for mass, #r# for "radius" (EX: half the length of a rod if it's rotated about its center), and #vecomega# for rotational velocity (#vecomega*vecomega = omega^2#, a scalar).

Linear Potential Energy:

#U_L = mvecgDeltavecy#
with #m# for mass, #vecg# for gravity, and #Deltay# for vertical displacement (#vecg*Deltavecy = "scalar"#)

Elastic Potential Energy:

#U_E = 1/2 kvecx^2#
with #k# for a force constant and #vecx# for the displacement of the compression or stretch (#vecx*vecx = x^2# is a scalar).

...and all of these types of energies have units of some type of #J#.

None of these energies are directional. The sign merely indicates whether it left system A and went into system B (negative with respect to A), or came into system A from another system B (positive with respect to A).