Translation:The fence around the garden is beautiful.
My doubt was: unlike the "Wechselpräpositionen", which can be used with both dative and accusative - depending on the motion -, is "um" always always used with accusative? In the example "Wir rennen um das Haus" there's motion and accusative is used; in the example "Der Zaun um den Garten ist schön" there's no motion and again accusative is used. When learning about dative-and-accusative prepositions, I was told that you know if there is motion when the preposition is introducing the destiny, like in "Das Buch fällt auf den Tisch", but I noticed that when you're talking about something going around something there is no destiny, so is that why "um" is always used with accusative?
My best guess is that there is (implied) motion in the words even if the fence itself is not moving.
The fence around the garden is a fence that "goes around" or "runs around" the garden. It can even "run along the perimeter" or "run the length" of the garden. For some reason, we rarely talk about a fence just sitting or standing in place.
Seems to be a modification of a 19th C response Tsk Tsk meaning nonsense. As used in this thread it's harmless enough. If you were using "tosh" face to face in conversation, you may come across as being verbally dismissive/aggressive. We find it useful during political conversations :-)