kanojo 彼女, Meaning in Japanese: She, Her, Girlfriend

In Japanese, kanojo 彼女 means "she," "her," a female third person pronoun, or "girlfriend."

It's the female counterpart of kare 彼, "he," "him," "boyfriend."

Third Person Pronoun

The word kanojo 彼女 is a female third person pronoun.

kanojo wa Hanako desu
彼女は花子です
She is Hanako.
kanojo wo tasukeru
彼女を助ける
To help her.
kanojo-tachi
彼女たち
She and the others. They.
(plural.)
kanojo-ra
彼女ら
(same meaning, less common.)
kanojo no
彼女の
Her.
Hers.
(no-adjective.)
kanojo-tachi no
彼女たちの
Their.
Theirs.

Japanese is a pro-drop language, so it's not necessary to use kanojo in some places we'd use "she" in English, if it's implicit whom we're talking about. For example, in the answer for a question:

Hanako wa nani wo shite-iru?
花子は何をしている？
What is Hanako doing?
benkyou shite-iru
勉強している
[Hanako] is studying.
[She] is studying.
- kanojo wa benkyou shite-iru
  彼女は勉強している
  She is studying.
  (same meaning.)

"Girlfriend" in Japanese

The word kanojo 彼女 also means "girlfriend" in Japanese.

ore no kanojo
俺の彼女
~~My her.~~ (wrong.)
My girlfriend. (right.)
boku no kanojo
僕の彼女
(same meaning.)
kanojo wa iru?
彼女はいる？
Is she here? (locative.)
Do [you] have a girlfriend? (possessive.)
(existence verb.)
- kanojo wa koko ni iru
  彼女はここにいる
  She is here.
- ore wa kanojo ga inai
  俺は彼女がいない
  I don't have a girlfriend.
  (double subject construction.)
- ore wa {kanojo ga inai} to ikite-ikenai
  俺は彼女がいないと生きていけない
  If {she isn't [around]}, I can't go on living.
  I can't go on living if she isn't around.
  I can't live without her.
atarashii kanojo ga dekita
新しい彼女ができた
[I] made a new girlfriend.
mae no kanojo
前の彼女
The girlfriend of before. (literally.)
[My] previous girlfriend.
moto-kanojo
元彼女
Former girlfriend. Ex-girlfriend.

Manga: Danshi Koukousei no Nichijou 男子高校生の日常 (Chapter 2, 男子高校生と放課後)

naa, kanojo tte dou yattara dekin-no?
なあ　彼女ってどうやったらできんの？
Hey, what do [you] have to do to make a girlfriend?
- dekin-no - contraction of dekiru no できるの.