• 秒速びょうそく — speed per second
• 何秒なんびょう — how many seconds?
• 秒針びょうしん — second hand (clock)
• 数秒すうびょう — a few seconds
• 秒読びょうよみ — countdown
• 秒殺びょうさつ — instant kill / win in seconds

秒 is made up of 禾 (grain) and 少 (few), which together express something tiny or minimal — just like a second, the smallest unit of standard time.

五秒ごびょうだけ待まってください。
Please wait just five seconds.

秒速びょうそくは 時速じそくに換算かんさんできます。
Speed per second can be converted to speed per hour.