In Tagalog grammar, nouns play a crucial role in forming the structure of sentences. Nouns are words that represent people, places, things, and ideas. They can be singular or plural, and can also be classified into concrete nouns and abstract nouns.

Concrete nouns refer to things that can be seen, touched, heard, or tasted, such as “table,” “dog,” and “music.” On the other hand, abstract nouns represent ideas, emotions, and qualities, such as “love” or “happiness.”

Nouns in Tagalog also have the concepts of case and possession. There are three cases: nominative, genitive, and oblique. The nominative case is used for the subject of the sentence, while the genitive case indicates possession. The oblique case is used for indirect objects and objects of prepositions.

In addition, nouns in Tagalog undergo affixation to express grammatical relationships. Affixes are added to the root word to create new words. For example, the verb “luto” (to cook) can become the noun “lutuan” (kitchen) by adding the affix “-an.”

Overall, understanding the theory of nouns in Tagalog grammar is essential for constructing clear and coherent sentences in the language.