How to say..can you please say it again a little slower?
这个对吗？

你可以说再一遍吗？ = can you please say that again?

你可以说再一遍慢一点儿吗？ or 一点儿慢？ = can you say that a little slower please?Like what is the difference between
慢一点儿 or 一点儿慢？

and when do we use it?

Question

How to say..can you please say it again a little slower?
这个对吗？

你可以说再一遍吗？ = can you please say that again?

你可以说再一遍       慢一点儿吗？  or       一点儿慢？  = can you say that a little slower please?Like what is the difference between
慢一点儿   or   一点儿慢？

and when do we use it?

Answer

你可以說慢一點嗎？

Answer

Can you say that a little slower please?
In Chinese: 你可以说慢一点儿吗？

The difference between 慢一点儿 and 一点儿慢is
慢一点儿means： slow down
一点儿慢means：a little bit slow

Hope it can help you :D

Answer

你走路慢一點兒
> 走太快會跌倒
> 要求 或 禁止 或 叮嚀

你走路有一點兒慢
> 你跟不上我的腳步
> 抱怨對方

Answer

你可以 再說一遍 嗎？

你可以 再說一遍 慢一點兒 嗎？

你可以 慢一點兒 再說一遍 嗎？