2(Al)2Br3 + 3Cl2 (arrow pointing right) 2Al(Cl)3 + 3Br2 in model form as soon as possible! Please help me!! :)

Al2Br6 is what you had to put up there and Al2Cl6

The initial molecule is AlCl3 and AlBr3 but since the aluminium has a vacant orbital, it can accommodate a pair of electrons from another surrounding molecule and thus, dimerise (form a molecule from two similar molecules)

Note that this bond between the two smaller molecules is a dative bond.

A drawing of it can be like this:

XX

Where the center of the X is the Al, and the ends of the X being the chloride or bromide ions.

Br2 and Cl2 are drawn as Br-Br and Cl-Cl respectively.