What is what part of speech is that?

A part of speech (also known as a word class or grammatical category) is a category of words that have similar grammatical properties. Words that are assigned to the same part of speech generally exhibit similar behavior in terms of syntax—they play similar roles within the grammatical structure of sentences—and sometimes in terms of morphology, in that they undergo similar inflections.

The main parts of speech in English are:

• Nouns: Words that represent people, places, things, or ideas.
• Pronouns: Words that replace nouns or noun phrases.
• Verbs: Words that describe actions, occurrences, or states of being.
• Adjectives: Words that modify or describe nouns or pronouns.
• Adverbs: Words that modify verbs, adjectives, or other adverbs.
• Prepositions: Words that show the relationship between a noun or pronoun and other words in the sentence.
• Conjunctions: Words that connect words, phrases, or clauses.
• Interjections: Words that express strong emotion or surprise.

Some sources also include Determiners (like "the", "a", "an", "this", "that") as a separate part of speech.

Understanding the parts of speech is fundamental to understanding grammar and constructing well-formed sentences. The specific classification and terminology used can vary depending on the grammatical framework being used.