A noun is a person, place or thing.  "Proper nouns"  are the names of people, places or things, such as "Philadelphia," or "Ben Franklin."  All nouns in Arabic are either "masculine" or "feminine" in gender.  In this way, Arabic is similar to most European languages, such as French, Spanish or German, which all have genders for their nouns.   This makes sense when you're talking about nouns that are for people, such as:

Masculine Human Nouns

Mudarris - male teacher
Ustaath - male professor
Waalid - father
Walad - boy
Akh - brother
Jadd -  grandfather

Feminine Human Nouns

Mudarrisa - female teacher
Ustaatha - female professor
Waalida - mother
Bint - girl
Ukht - sister
Jadda - grandmother

But for speakers of English, it can be confusing to talk about the gender of non-human objects, such as the following:

Masculine Non-human Nouns

Kitaab - book
Ism - name, noun
Baab - door
Al-Maghrib - Morocco
Qalam - pen
Dars - lesson
Bayt - house
Arnab - rabbit

Feminine Non-human Nouns

Madrasah - school
Sayyaarah - car
Lughah - language
Mir - Egypt
Madiinah - city
Taawilah - table
Ziraafah - giraffe

Fortunately, in Arabic it is usually easy to tell if a noun is masculine or feminine.  Look at the examples above.  You will notice that most of the feminine nouns end with an "-ah" sound.  This is how you can tell that the noun is feminine.  It's a lot easier than French or German, where you have to memorize the gender of every noun.  However, for some proper nouns, like Misr or al-Maghrib, you still need to memorize whether it's masculine or feminine.

An adjective is a word which describes a noun.  Here are some common adjectives:

Adjectives

Kabiir - big
aghiir - small
Jadiid - new
Qadiim - old
Jamiil - beautiful
Tawiil - long, tall
Qaiir - short
a^cb - difficult
Sahl - easy

In Arabic, the adjective follows the noun it describes--the opposite of English. An adjective must "agree" in gender with the noun it describes:  If the noun is masculine, the adjective must be masculine.  If the noun is feminine, the adjective must be feminine.  You make the adjective feminine simply by adding the "-ah" sound at the end.  Look at the following examples:

Kitaab qadiim = an old book

Walad jamiil = a handsome boy

Taalib jadiid = a new student

Baab aghiir = a small door

Bint jamiilah = a beautiful girl

Sayyaarah jadiidah = a new car

Madrasah kabiirah = a big school

Lughah qadiimah = an ancient language

An adjective must also agree with the noun it describes in "definiteness".  Remember, you make a noun definite in Arabic by adding the "al-" (The) at the beginning.  (Arnab = rabbit, al-arnab = the rabbit)   So if the noun has an "al-" the adjective which describes it also has to have an "al-."  Look at the following examples:

bayt qadiim = an old house
al-bayt al-qadiim = the old house

walad awiil = a tall boy
al-walad a-awiil = the tall boy

dars a^cb = a difficult lesson
ad-dars a-a^cb = the difficult lesson

qalam jadiid = a new pen
al-qalam al-jadiid = the new pen

aawilah jamiilah = a beautiful table
a-aawilah al-jamiilah = the beautiful table

madiinah kabiirah = a big city
al-madiinah al-kabiirah = the big city

lughah sahlah = an easy language
al-lughah as-sahlah = the easy language

Mir al-qadiimah = ancient Egypt
(Egypt is a proper noun, so it is definite)

Notice that with some of the words above, the "al-" has changed to "at-," "as-," etc.  This has to do with the way the "definite article" Al- is pronounced in combination with certain letters.  We will talk more about that later.  For now, just pronounce the words the way they are written above.