well the thing is, tell/talk/inform or anything alike, then 说 is ok~
There are tons of other words to express more sophisticated implicated meanings but only with 说 you can do a lot.
E.G ; you were telling your friend what assignment has been given,
我在和朋友说/作业是什么/
or you want to discuss with your flatmate about something (perhaps wifi bill)
我们说一说这件事情(of course 聊一聊/谈一谈 communicate basically the same meaning here, just, chat)
They are talking about me?
I imagine it's like when you pass by and hear two other people chatting, maybe about u : p
Then you just randomly ask : hey, 你们说我什么?/你们在说什么?the same as what's up~