This is the 30th most frequent Czech word.
let
"Let" in Czech means "year" or "flight," depending on the context.
In this sentence, 'let' is used as a noun to mean 'years', which is the plural of 'rok' (year). It denotes a period of time.
Už je to deset let, co jsme se neviděli.
It has been ten years since we last saw each other.
Here, 'let' functions as a noun meaning 'flight', describing the act or process of flying.
Let ptáků vypadá elegantně na obloze.
The flight of birds looks elegant in the sky.
In this instance, 'letím' is a conjugated verb form meaning 'I am flying'. It comes from the verb 'letět' which means 'to fly'.