Please explain the damping term differential equation below

Please explain the damping term (differential equation) below. Give one or two paragraph (The alpha letter B is the beta symbol).

m d2x/dt2 + B ldx/dtl dx/dt + kx =0

Thank you, please give detail information

the middle term of the given equation is a Dampening term the Dampening term always come with dx/dt and the coefficient of dx/dt is called dampening coefficient