Questions & Answers about अभी पानी ठंडा है।
In this sentence, अभी means now, right now, or at the moment.
It gives the sentence a current-time feeling: the water is cold at this time.
A useful warning: अभी can mean slightly different things in other contexts, such as just now or even soon, so you always have to read it in context. But in अभी पानी ठंडा है, the natural reading is right now.
Hindi normally does not use articles like a, an, or the.
So पानी can mean:
- water
- the water
The context tells you which one sounds best in English.
If Hindi wants to be more specific, it can use words like यह (this) or वह (that), but very often no article is needed at all.