  We investigated the ionised and atomic gas kinematics and excitation state in
the central region of ongoing star formation of the nearby low-metallicity
dwarf galaxy Sextans B. The analysis is based on the new observations performed
in Ha emission line with high resolution ($R \sim 16000$) scanning Fabry-Perot
interferometer at the 6-m BTA SAO RAS telescope, and on the long-slit spectral
observations at the 9.2-m SALT and 2.5-m CMO SAI MSU telescopes. Strong
non-circular gas motions detected in the studied regions probably resulted from
the off-plane gas motions and impact of stellar feedback. We identified six
regions of elevated Ha velocity dispersion, five of which exhibit asymmetric or
two-component Ha line profiles. Three of these regions are young ($<1.1$ Myr)
expanding ($V_{\rm exp} \sim 25-50\ {\rm km\ s^{-1}}$) superbubbles. We argue
that at least three regions in the galaxy could be supernova remnants. We
conclude that supernovae feedback is the dominant source of energy for
superbubbles in Sextans B, which is expected for such a low metallicity,
although we cannot rule out a strong impact of pre-supernova feedback for one
superbubble.
