what's happening here?
a joke about Akagi line that said she don't know about Reppu?

Added a few notes and amended some of Akagi-san's lines. Translation check is sorely needed here ^^;;;

Strela said:

what's happening here?
a joke about Akagi line that said she don't know about Reppu?

I'm not familiar enough with KanColle (Never played it), but could it be regarding the cost of resources to create the planes, or just implying Akagi ate lots of Bauxite as usual?

she looks at reppuu as a snack to eat rather than a plane to fight

It's because the Reppu (a very valuable equipment) was developed after Akagi sank, so she doesn't know about it. She's saying that it's a snack as a reference to how much she likes to eat and how you're able to scrap and convert equipment into resources in the game. Obviously since the Reppu is so valuable, you wouldn't do that, hence Kaga and the Admiral's anger at Akagi.