In this compound, the parent chain is the one containing cyclic carbon.

Now, we number in the following way. 

Because more substituted will get the lower number.

$\to$ethyl group at $C_5$

$\to$Two methyl group at $C_3$

Therefore, it will be

      6-Ethyl-3-3-Dimethylcyclohex-1-ene

                             not

      3,3-Dimethyl-6-ethylcyclohex-1-ene

Because we use alphabetical order and Di- is not considered for the alphabetical order.