what does 'there'll be a right old row if my dad gets to hear about it" means??

sophie says this to jansie because when she comes to know that geoff has told frank(jansie's brother) about her meeting with danny casie and jansie even know this she told jansie not to tell her father(sophie's father) about this otherwise there will be a big argument that will take place between sophie and her father...

(actually at this phase sophie didn't knew that jansie don't knows about the date'she thinks that geoff has told everything to frank).