Hi.
If we assume your candles are on a 1 hour chart and you’re looking at the 9:00-10:00 candle for simplicity.
OPEN is the price at 9:00
CLOSED is the price at 10:00
HIGH is the highest point price reached between 9:00 and 10:00
LOW is the lowest point price fell to between 9:00 and 10:00
Hope that helps