Bar chart is a visual way to represent  Open, High,Low, Closing pricing movements of the security. 
A single bar has a vertical line, left horizontal tick and right horizontal tick.
    Vertical line indicates the high-to-low price range.
    Left horizontal tick shows open price.
    Right horizontal tick shows closing price.
Bar charts help a trader/investor  visualise bullish sentiment ( upward / uptrend  price movement on chart ) or bearish sentiment( downward / downtrend  price movement on chart ) by displaying bars using different colours.

Bar Chart -4

A bullish bar is one in which the price has closed higher than it opened  – the vertical line of such bar is usually represented in green.

Bar Chart -3

A bearish bar  is one in which price has opened lower than it opened  –  the vertical line such a bar is usually represented in red.

Bar Chart -Example

Difference between high price and low price is called range.

Practice Bar Chart – Beginner

Practice Bar Chart – Intermediate

Practice Bar Chart – Advanced

Practice Bar Chart – Expert