The structure of ${\mathrm{BF}}_3$ can be shown as follows,

Three hybrid orbital are required to form ${\mathrm{BF}}_3.$ Hence, the hybridisation of Boron is ${\mathrm{sp}}^2$ and the number of electrons around the boron is $6$ due to the presence of three $\mathrm{B}-\mathrm{F}$ bonds.