Number of lone pair(s) of electrons on central atom and the shape of ${\mathrm{BrF}}_3$ molecule respectively, are

There are three sigma bonds and two lone pairs on BrF₃ molecule.

$$\begin{gathered} \mathrm{Steric} \mathrm{number}=\mathrm{No}. \mathrm{of} \mathrm{sigma} \mathrm{bonds} \mathrm{on} \mathrm{central} \mathrm{atom}+\mathrm{No}. \mathrm{of} \mathrm{lone} \mathrm{pairs} \mathrm{on} \mathrm{central} \mathrm{atom} \\ =3+2 \\ =5 \left({\mathrm{sp}}^3\mathrm{d}\right) \end{gathered}$$

Because of having two lone pair of electrons, it has a bent T-shape shape.