# Energy density in Magnetic fields?

I don't understand what does magnetic field energy density stand for? The possible work that the magnetic field can do? So we can calculate the amount of "work" it can do just from the energy density?

Example: A magnetic field is created by a solenoid, there is a energy density of 10J/m3. From that can I derive the magnitude of magnetic force using work = F*d Thus, it would be F = W/d?

$\eta=\frac{B^2}{2\mu_0\mu_r}$