Translation:They have good service at this hotel.
According to Wiktionary, "good service" (as in, it's your job to treat people well and you're doing that job well) is used with an article in British English and without one in American English. I'll leave it up to the mods to determine if with the article should be accepted, but keep in mind that American English is default on Duolingo.
It's a bit complex. Traditionally it was considered correct to say either det här hotellet or detta hotell. The thing is that detta hotell sounds very formal. Basically no one says that in real life. In the parts of the country where people use detta, they normally say detta hotellet. But that in turn is pretty colloquial. There isn't really a stylistically neutral version with detta + noun.
So you should be aware that detta hotellet isn't suitable for formal texts, but it's still acceptable (and very common in some parts of Sweden). It wasn't an accepted answer here but we usually accept that form too, so I've added it here now.