What it means
たがる expresses a desire that the speaker observes in another person or group. It normally attaches to the masu-stem of a verb and means that someone seems to want to do that action or is eager to do it. The plain form is used in familiar contexts, while たがります is the polite counterpart.
Usage note
たがる is generally used for someone other than the speaker. To describe your own desire, use たい instead. For a desire that is visibly continuing or repeatedly shown, たがっている is also common.
How to use it
弟は寿司を食べたがります。
The younger brother wants to eat sushi.
弟は寿司を食べたがる。
The younger brother wants to eat sushi.
Example sentences
弟は自分で自転車を直したがっています。
My younger brother wants to fix the bicycle himself.
母は来月の旅行で京都の寺を見たがっています。
My mother wants to see the temples of Kyoto on next month's trip.
妹は新しい絵の具を使いたがっています。
My younger sister wants to use the new paints.