Here the example question says identify the type of functional group or groups present within the following compound. Remember look for your landmark elements sun or halogens.
If we take a look here, we have an oxygen. We're going to say that oxygen looks like it's connected to what, a carbon here and a carbon here. Those carbons, we don't see double bonds or triple bonds connected to them. So they're just regular single bonded carbons connected to an oxygen.
And remember, when we have Coc, that represents an ether functional group. So here our only functional group within this structure would be our ether.