/jp/ - Otaku Culture

Newbie here. Everyone says you should just jump in and start reading, but how am I supposed to do this? I'm just looking up the words on jisho, but this panel for instance.
でも = "but"
わかんない = "not understanding or not knowing" (this is wakaru + nai, right? wakaru is an ichidan verb?)
よ = a particle that ends a sentence for emphasis or to get attention (?)
The English translation is "but, you never know..."
How would I have gone about getting that translation? And how am I supposed to get grammar by doing this? I've posted about trying to learn grammar before but people just tell me to read and I'll get it through exposure.
Also, the second speech bubble apparently mentions hail, but I didn't see the word for hail in there.