I can only figure about half of this one out:

Your assignment is to go back and label the parts of speech of each word in this paragraph. The only ones which you do not know are articles (a/the) and determiners (these/those/this/that).

There are: nouns, pronouns, verbs, adverbs, adjectives, prepositions, and conjunctions.

The Sentences:
She strode to a door in the far corner of the office, opened it, and called a name. A boy appeared in the doorway. He sat down at one end off the table. He was brown like us, a plump kid with shiny black hair combed straight back, neat, cool, and faintly obnoxious.

I only know what nouns, verbs, and adjectives are, and have a vague idea on pronouns, adverbs, and conjunctions. No clue what prepositions are.

Could someone explain them to me? I tried Google but it doesn't make much sense.... Thanks in advance....

The first site gives good descriptions of all of the parts of speech.

http://eslus.com/LESSONS/GRAMMAR/POS/pos.htm

The definition of preposition is difficult to understand. I suggest you keep a list of the common prepositions handy. Then learn to recognize prepositional phrases; they start with a preposition and end with a noun or pronoun.
Examples:
to me
by the back door
from Harry and Peggy
under the rose bush
toward a strange woman

Here's a list of prepositions:

http://www.englishclub.com/grammar/prepositions-list.htm

The best way to understand what prepositions are is simply to memorize the words. Fortunately that's pretty easy!

http://grammar.ccc.commnet.edu/grammar/prepositions.htm
Notice all the words in blue in the quoted paragraph.

Here's another article that explains them well: http://grammar.ccc.commnet.edu/grammar/prepositions.htm
Mainly pay attention to the words in the first paragraph.

http://members.cox.net/lenco1/grammarpractice/
This should help with various types of words that you've been assigned to identify.

And another: http://www.leasttern.com/Grammar/humbuggrammar.html

And yet another: http://www.chompchomp.com/terms.htm

Thank you so much!

A quick suggestion about prepositions.

I used to tell my student, "Any word that shows the relationship between a rabbit and a hill." Examples:

the rabbit "on" the hill, "by" the hill, "near" the hill, "below" the hill, "under" the hill. etc.

This is just a little "trick" that helps remember.

Of course! I can explain the different parts of speech for you. Let's start with the ones you already know:

1. Nouns: These are words that name people, places, things, or ideas. In the paragraph, examples of nouns include "door," "office," "name," "boy," "end," "table," "hair," and "kid."

2. Verbs: These are words that describe actions, occurrences, or states of being. In the paragraph, examples of verbs include "strode," "opened," "called," "appeared," "sat," "was," "combed," and "obnoxious."

Now, let's move on to the parts of speech you mentioned having a vague idea about:

3. Pronouns: These are words that are used in place of nouns to avoid repetition. Common pronouns include "she," "he," "us," "it," and "they." In the paragraph, "she," "it," and "he" are used as pronouns.

4. Adjectives: These are words that describe or modify nouns. They provide more information about the noun. In the paragraph, examples of adjectives include "far," "black," "straight," "neat," "cool," and "faintly."

5. Adverbs: These are words that describe or modify verbs, adjectives, or other adverbs. They provide information on how, when, where, or to what extent something happened. In the paragraph, there is only one adverb used - "obnoxiously" modifies the verb "combed."

Next, let's discuss the part of speech you mentioned not knowing:

6. Prepositions: These are words that show relationships between nouns or pronouns and other words in a sentence. They indicate location, time, direction, manner, or possession. Common prepositions include "to," "in," "on," "at," "from," "with," "of," and "by." In the paragraph, examples of prepositions include "to," "in," "of," and "at."

Lastly, we have:

7. Conjunctions: These are words that connect words, phrases, or clauses in a sentence. They can show relationships like addition, contrast, cause and effect, or time. Common conjunctions include "and," "but," "or," "because," "if," and "when." In the paragraph, there is only one conjunction used - "and" connects the verbs "opened" and "called."

To label the parts of speech in the paragraph, you would identify the specific word and determine which category it falls into based on its function in the sentence. You can refer to an online resource, grammar book, or dictionary to help you identify unfamiliar words or clarify any doubts.