...speed in TMA Praha is restricted by so called SLP (Speed limit point)?
No matter if you fly on the stadart arrival route or you are vetored by ATC, while entering the TMA Praha, you must always decelerate on the speed that meets the limit or less. These limits are shown on each of the arrival charts.
In addition, bellow flight level 100 the speed must be reduced to 250 knots IAS or less. This speed limit is valid also in case when ATC gives "no speed restrictions" instruction.