Step-by-step explanation:
When electrons are shared by two atoms then it results in the formation of a covalent bond.
Both chlorine and fluorine are non-metals and are electron deficient in nature. Therefore, when both of them combine then they tend to share the electrons and thus they form covalent bond.
Since fluorine is more electronegative than chlorine, therefore, a partial positive charge will develop on chlorine and partial negative charge will develop on fluorine atom.
Thus, we can conclude that the arrow shows that the bond between the chlorine atom and the fluorine atom is covalent. The electrons in the bond are pulled towards fluorine atom, and the chlorine atom is partially positive.