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Hexafluorocobaltate(III) ion is a high-spin complex

The complex with the same number of unpaired electrons as the free metal ion is termed a high-spin complex and it has the maximum number of unpaired electrons. High-spin complexes occur when weak-field ligands bond with central metal ions because they cause small splitting energy.

Weak-field ligands give smaller splitting energy $(∆)$ because they don't cause large splitting oforbitals (F- is a weak-field ligand).

${\left[{\mathrm{CoF}}_6\right]}^{3-}$ in this complex Co has an oxidation state 3+, so the number of electrons in its d subshell is 6. The electron configuration of Co is $3{\mathrm{d}}^{7}4{\mathrm{s}}^2$. In this complex, there are two higher energy ( ${\mathrm{e}}_{\mathrm{g}}$) orbitals and three lower energy ( ${\mathrm{t}}_{2\mathrm{g}}$ ) orbitals formed.