In this sentence, what part of speech is the word Teresa's: Teresa's parents have formed a service organization for the community.

Teresa's = possessive

Sra

P.S. As for the part of speech, it is a proper noun.

Sra

To identify the part of speech for the word "Teresa's" in the given sentence, you need to understand the concept of possessives and how they function in English grammar.

1. First, recognize that "Teresa's" is formed by adding an apostrophe and the letter "s" to the proper noun "Teresa." This construction indicates possession or ownership.

2. In this sentence, "Teresa's" functions as a possessive noun, specifically indicating that the parents belong to or are associated with Teresa.

3. As a possessive noun, "Teresa's" functions as an adjective because it modifies the noun "parents" by showing possession or ownership.

Therefore, in the given sentence, the word "Teresa's" functions as an adjective.