Es entstehen ganz neue Wohnformen.
how could this be translated?
I am not so good in English, but it means, that there arise completely new ways to live (= living forms?)
In example, in the past, families were bigger and used to live together, while in the present more and more people are living alone. Nowadays, because the retirement pensions get lower, older people think about living in a flat shares instead of living alone or in a rest home, so they can support each other. These are some of "Wohnformen". But it can also mean new facilities and infrastructures to live together and so on, depending on the context.
In this case 'es' is best translated as 'there'. 'Wohnformen' (lifestyles?) is the subject (so nominative) and the verb is 3rd person plural.
'Es sind vier Kartoffeln' 'There are four potatoes' instead of 'Es gibt vier Kartoffeln' is another example of 'es' used this way. 'Sein' is plural 'sind' to agree with 'potatoes.' 'Es gibt...' is the common way of saying 'There are....'
You are welcome. Recently I found a nice article about the german cases:
It is written from the view of an English speaking person. Perhaps the content will help you to understand the cases a little better?