Using pp collision data corresponding to an integrated luminosity of 5.4 fb-1 collected with the LHCb detector at a center-of-mass energy of 13 TeV, the B0→D-D+K+π-decay is studied. A new excited Ds+ meson is observed decaying into the D+K+π-final state with large statistical significance. The pole mass and width, and the spin parity of the new state are measured with an amplitude analysis to be mR=2591±6±7 MeV, ΓR=89±16±12 MeV, and JP=0-, where the first uncertainty is statistical and the second systematic. Fit fractions for all components in the amplitude analysis are also reported. The new resonance, denoted as Ds0(2590)+, is a strong candidate to be the Ds(2S10)+ state, the radial excitation of the pseudoscalar ground-state Ds+ meson.