A longer chart interval used for context; its levels and trend tend to dominate shorter-term signals.
How timeframes stack up. A daily candle is not different data, only coarser data: it opens where the first six-hour candle opened, closes where the last one closed, and its wicks reach the highest and lowest prices any of the four touched.
When traders say a level is higher-timeframe, they mean it was formed on a daily, weekly or monthly chart and is therefore visible to far more participants than a 5-minute swing point.
Higher timeframe bars contain more information per bar and produce fewer, slower signals. That reduces noise and transaction costs, but also means a stop must be wider and a mistake takes longer to reveal itself.
A practical use: mark weekly and daily swing-highs and swing-lows, the prior-day-high-low, and the weekly-open on your intraday chart. Most intraday reversals happen near something, and that something is usually a higher timeframe reference rather than an indicator crossing.