再说 has two meanings. 1) it means besides. for example: "relax mom, I can take care of myself. besides, my uncle lives just over there. I can find him if necessary." 放心吧妈妈，我可以照顾我自己。再说(besides)，我舅舅就住在那儿，如果需要的话我可以去找他。 2)some problem should be solved but you dont want to solve it right now. you can say 再说（吧） for example, your friend invites you to go shopping, but you dont want to. then you can say: 再说 or 再说吧，我现在很忙(I am very busy now)。 here 再说 means let's talk about it later.

1再说=另外（比另外的语气要重一些）。its kinda like besides。e.g:我不想去吃饭，再说，现在才4点。I dont want to have a dinner,besides,it's 4 o'clock.

再 = again 说 = say an adverb and a verb