"キャパ” read kyapa (or kapa) and means capacity "ちいせーんだろうな” read chiiseen darou na and means is really small(or low) and it basically translates to "his capacity is really low"
btw forgot to say the line before it but the whole line "柴ちゃんってキャパちいせーんだろうな” read shiba chan tte kyapa chiisen darou na and means "shiba-chan's capacity is really low"
"キャパ” read kyapa (or kapa) and means capacity "ちいせーんだろうな” read chiiseen darou na and means is really small(or low) and it basically translates to "his capacity is really low"