Whats does "hr" mean among "V" and "Ah" in batteries?
It means that the battery has a capacity of 25 Ah when discharged in 10 hours. 25 Ah is 25 Amps for 1 Hour which is equivalent to 2.5 Amps in 10 Hours.

So if you load the battery with 2.5 Amps it will last 10 Hours.

If loaded with a higher current usually battery capacity decreases so that is why the 10 Hours is mentioned, it results in a higher battery capacity making the battery look "better".

How many watts: simple 2.5 Amps x 12 V = 30 Watts and that for 10 Hours.