It's a common saying that indicates time has value. To do work takes time, which is a limited resource that in the short term we all have the same amount of. The rich do not get 25hrs per day nor do the poor get only 23hrs. All of humanity gets a 24hr day.
You're hanging out in that random voice call with your friends talking about whether cats would enjoy eating tacos. And then you see it in your DMs or a public chat section:
You're in a chatroom typing with others and everything is going great! Conversation is flying! Until it slows down, or suddenly stops. And then you see it: