  The spectroscopic parameters and decay channels of the scalar tetraquark $
T_{bb;\overline{u}\overline{s}}^{-}$ (in what follows $T_{b:\overline{s} }^{-}
$) are investigated. The mass and coupling of the $T_{b:s}^{-}$ are calculated
using the two-point sum rules by taking into account quark, gluon and mixed
vacuum condensates up to dimension 10. Our result for its mass $m=(10250 \pm
270)~\mathrm{MeV}$ demonstrates that $T_{b:\overline{s}}^{-} $ is stable
against the strong and electromagnetic decays. Therefore to find the width and
mean lifetime of the $T_{b:\overline{s}}^{-}$, we explore its dominant weak
decays generated by the transition $b \to W^{-}c$. These channels embrace the
semileptonic decay $T_{b:\overline{s}}^{-} \to
Z_{bc;\overline{u}\overline{s}}^{0}l\overline{ \nu }_{l}$ and nonleptonic modes
$T_{b:\overline{s}}^{-} \to Z_{bc;\overline{ u}\overline{s}}^{0}\pi^{-}(K^{-},
D^{-}, D_s^{-})$, which at the final state contain the scalar tetraquark
$Z_{bc;\overline{u}\overline{s}}^{0}$. Key quantities to compute partial widths
of the weak decays are the form factors $G_1(q^2)$ and $G_2(q^2)$: they
determine differential rate $d\Gamma/dq^2$ of the semileptonic and partial
widths of the nonleptonic processes, respectively. These form factors are
extracted from relevant three-point sum rules at momentum transfers $q^2$
accessible for such analysis. By means of the fit functions $F_{1(2)}(q^2)$
they are extrapolated to cover the whole integration region $m_l^{2}\leq
q2\leq(m-\widetilde m)^2$, where $\widetilde m$ is the mass of
$Z_{bc;\overline{u}\overline{s}}^{0}$. Predictions for the full width $\Gamma
_{\mathrm{full}}=(15.21\pm 2.59)\times 10^{-10}~\mathrm{ MeV}$ and mean
lifetime $4.33_{-0.63}^{+0.89}\times 10^{-13}~\mathrm{s}$ of the $T_{b:s}^{-} $
are useful for experimental and theoretical investigations of this exotic
meson.
