Pikachu puns aside, it is the full name of the yaku commonly referred to as tan'yao, aka All Simples (your winning hand composed of number tiles 2-8 exclusively).
Ron means nothing. It just means Pikachu went out (Got his last tile). Granola is talking about how many points would be given for going out with that formation.
"ron" is to win from another's discard and awards you 10 fu which could boost you to a mangan (worth 8000pts, or 12000pts if you're the dealer). How you win also determines how you collect your winnings: tsumo (self-drawn) in which the payment is split between the 3 other players (dealer pays half) or ron, where the discarder shoulders the entire payment.
What's certain is this hand has tanyao (all middles, no terminals or character tiles) and toitoi (all triples). If only one of the triples were called, then this hand would have sanankou (three closed triples) as well.
Finally if this hand was completely closed, it would actually be a yakuman (god hand, 32000pts, 48000pts if dealer) known as suuankou tanki machi (four closed triples, single tile wait) and is sometimes respected as a double yakuman (64000pts, 96000pts if dealer).