A timeframe (also called an interval) defines how much real time each individual candle or bar on a chart summarizes — a 5-minute timeframe means each candle covers five minutes of price action, while a daily timeframe means each candle covers one full trading day. Switching timeframes doesn’t change the underlying price history, only how it’s grouped and displayed; the right choice depends on trading style, with shorter timeframes suiting intraday trading and longer ones suiting swing trading or investing.
Related Reading
See how timeframe choice should follow from trading style, not the other way around, in Understanding Timeframes on TradingView.