${\text{BF}}_3$ is planar and electron deficient compound. Hybridization and number of electrons around the central atom, respectively are:

Boron in ${\text{BF}}_3$ has $3$ valence electrons. It forms $3$ sigma bonds with Fluorine.Number of hybrid orbitals = $3$ (zero lone pairs) $\Rightarrow s{p}^2$ hybridization (trigonal planar).Total electrons around Boron = $3$ (from B) + $3$ (from $3$ F atoms) = $6$ electrons.