Bar chart unfortunately has nothing to do with beer or snooker. However compared to line chart that only shows closing price bar chart also shows an opening price, highest price and lowest price all at the same time. So instead of a continuous line you get short vertical "bars" with little left and right "tails". The left tail shows the opening price and the right tail represents the closing price. Bar Chart is often called OHLC which stands for Open High Low Chart.
So, just so summarize:
Open = Opening price of the period represented by tiny horizontal tail on the left side
High = Highest price of the period represented by the TOP of the whole vertical bar
Low = Lowest price of the period represented by the BOTTOM of the whole vertical bar
Close = Closing price of the period represented by tiny horizontal tail on the right side