"How to say 'one hour' in English?"
In English, the expression for "one hour" is simply "one hour." There is no special way to phrase this as it is a basic concept that does not require any unique translation. However, if you want to express the duration of an event within one hour, you might use expressions such as "one hour has passed," "we have been working for one hour," or "the meeting will last for one hour."
It's worth noting that in some contexts, like when speaking about time in specific fields like aviation or military operations, there can be more precise ways to describe durations down to minutes and even seconds. But for everyday conversation and simple statements, "one hour" is the most straightforward way to express this idea.