Nouns in Japanese

At first sight nouns in Japanese are looking fairly simple, but there are some catches you should know about:

Gender
In Japanese there is no grammatical gender like male and female or something in between (like "it" in English).

Plural
Japanese usually doesn't have plural clarifications. This can lead to unclear sentences like: かみ may refer to god, goddess or gods in equal manner.
To express plurality in Japanese, you need to add counter words or attach words like "many" "few" etc.

People are exception in this aspect. They have four plural suffixes.

• The most commonly used is 〜達 (たち):
  わたし - I ,  わたしたち - We
  しょうねん- a boy, しょうねんたち - boys
  and so on.
  You also can say かまむらたち, which will mean Kamamura and others.

• A more honorable suffix for plural is ~ 方 (がた). Used in formal cases of writing a letter or addressing a honorable person. For example:
  せんせいがた - Mr. teacher.
  かまむらさまがた - Mr. Kamamura. 

• A less honorable suffix is 〜等 (ら), and it usually paired with nouns like わし (me), てめえ (you) etc.
  It also used to pluralize これ, それ, あれ.

• The last one is 〜供 (ども) and it used for someone you disrespect or to show modesty when saying わたしども.

Conjugation
To go over it lets take our beloved ねこ(cat) as an example. We have four forms affirmative/negative, present/past. Sadly Japanese have no future tense. So it goes like this:

Present affirmative: ねこです. present negative:  ねこではありません.
Past affirmative: ねこでした. past negative: ねこではありませんでした 

Affirmative  ~です and ~でした can be replaced with less polite:
~だ and ~だった

Negative ~ではありません and ~ではありませんでした can be replaced with: 
~じゃありません and ~じゃありませんでした- less polite 
~じゃない and ~ではなかった- least polite

Joining sentences with て form 

 For longer sentences you can use the て form (yes it's not exclusively for verbs).  Only in nouns it turns to で and a lot easier:

わたしはにほんじんで, にじゅうにさいです. - I'm Japanese and twenty two years old.

Listing nouns
In Japanese there are two ways to do it. With と or with や.
ねこといぬです - a cat and a dog.
ねこやいぬです - animals such cats and dogs (Meaning there are more than just these two).