Dogs have a lot more language than most people realize. We have a many generational large pack of livestock working dogs on our farm. Admittedly these dogs are more intelligent than a typical companion dog because they are selected for intelligence and spend their life doing herding, guarding and other tasks which stimulates their minds.
They typically know 300 words that is in a shared pidgin that we use which is a combination of signs, vocals (our language and theirs) and body language which describe objects (nouns), actions (verbs), variation (adverbs and adjectives) which they use in multi-word sentences. They both understand us, understand each other and speak back to us.
Some of the dogs understand and use as many as twice that and they actively make new signs to describe new things. This has previously been shown in other species. Dogs do it too.
Their biggest problem is their lives are so short. This is why having the multi-generational pack makes this behavior more noticeable - the dogs are passing on culture from generation to generation unlike dogs which are kept isolated in human families and treated as just a pet.