Don't have a clue on how to use this

I got the thingy that is supposed to go into the water and a little box that I had to put 2 batteries into.
This little box shows on the top line ------F
2nd line has the wordIN" and below that says 80F 30% with
Since it is not yet in the water why is it showing 80 F?
Should this change once I put it into the water?
Why are there 2 lines.with one saying Water temp and the next one saing IN?
Very confusing to me.

May I know that the product you are using is IBS-P01R?
If yes, the IBS-P01R-I receiver has a built-in temperature and humidity probe, and the IBS-P01R-O transmitter has a built-in temperature probe.
IN represents the temperature and humidity of the environment where the IBS-P01R-I receiver is placed.
Water temp is the temperature detected by the IBS-P01R-O transmitter.
If the batteries are installed, but the IBS-P01R-I receiver shows — F on the top, please pair the IBS-P01R again.