This is the 2122nd most frequent Russian word.
тсн
The word "тсн" does not hold meaning in Russian as it stands; it may be a typographical error or abbreviation requiring clarification.
The word 'тсс' is used here as an onomatopoeic sound representing the act of shushing to request quieter behavior.
Тсс, не шумите, пожалуйста.
Shh, please don't make noise.
In this context, 'тсс' is again an expression used to urge silence so that the speaker can concentrate on perceiving a sound.
Тсс, я думаю, что-то слышу.
Shh, I think I hear something.
Here, 'тсс' signifies a cautionary alert to maintain silence to avoid disturbing someone resting.