“Grammar as form” how would you describe it with example?

The representation of the way in which a sequence of words comes to be a well-formed sentence of a language. In a formal or artificial language grammar is laid down in formation rules, but the formation rules of natural languages are sufficiently complex to make accurate codification hazardous.

The basic goal of grammar is to provide an understanding of the sentence — the topmost element of the grammatical hierarchy. However, the idea of a sentence is not entirely clear-cut and defineable; for one thing, it is often difficult to say where one sentence ends and another begins. Because of this, it is best to begin doing basic grammar with a consideration of the next lower member of the hierarchy, the clause, and at a further point, to base an explanation of sentences on a prior understanding of clauses.

As you can see this can be defined in a number of ways, but none-the-less...... "grammar as form," is what make a sentence understandable. There are many different examples of a number of different rules for from. Do you have a specific structure in mind.

It is now possible to employ a fully communicative approach to language teaching while at the same time attending to grammatical structure, but only if one can decisively abandon a mindset in which structure consists of rules governing form only and fully adopt instead a view that structure consists of forms that encode meanings, which speakers choose in order to communicate messages. Across a wide range of linguistic theoretical frameworks, the construct of the rule (i.e., a manipulation of purely formal properties of language) has been rejected as a device of grammatical description. This change includes both the most formal of traditions, principally the Minimalist Program (Chomsky 1995), and the most functional, among them systemic functional linguistics (Halliday 2004), Cognitive Grammar (Langacker 1987), the Columbia School (Diver 1995), and construction-based functionalist linguistics (see e.g. Noonan 1999).