Questions & Answers about Насыпь немного сахара в чай.
Насыпь is the singular informal imperative of the perfective verb насыпать.
So it means something like:
- add
- pour in
- sprinkle in
It is addressed to one person you would say ты to.
Because насыпь sounds more natural for one completed action: add some sugar.
- сыпь comes from the imperfective verb сыпать
- насыпь comes from the perfective verb насыпать
In commands, Russian often uses the perfective imperative when you want someone to do a single action and finish it.
So:
- Насыпь немного сахара... = add some sugar
- Сыпь... can sound more like keep pouring / go ahead and pour, with more focus on the process