Can animals communicate with one another?
Of course they can. Life would be pretty miserable to all species on earth if they were unable to communicate. We can only communicate with a percentage of humans because of language barriers so must rely on other non-verbal methods to get by, animals do all that to a much more developed level.
We recognise a smile or scowl on the face of an approaching stranger to assess our first contact and depending on the first impression we greet with an extended hand or a weapon. Animals do exactly that too , but much deeper.
We may resort to gestures or signals to try to communicate, animals turn to scent signatures for the same purpose. Then follows growls or purrs or whatever, to indicate where it is going from there.
The methods of animal communications are varied and complex, they vary enormously from one species to another, but the have common standards as mentioned above where you are in no doubt about whether it will be friendly or not at first encounter.
Their greatest advantage lays in the assessment of bodily indicators such as deportment and facial expression which reduces enormously the ability to lie or present a false front as is common in humans with our total reliance on words.
I have found over many years that our animals are far better at assessment of strangers and I have come to rely on their senses in preference to our own.