Heikin-Ashi is a specially built candlestick chart. In fact, this technique averages price data to create Japanese candlesticks. To build a candle, we use information about the opening/closing prices of the previous candle and the information about the price change at that moment. Therefore, formally, Heikin-Ashi is an indicator, not a chart.
Heikin-Ashi smoothes price fluctuations and simplifies the analysis of trends, which means that using it makes it easier to find the opening and closing times of trades.