Mixing up “say” and “tell” is a common error among English learners. The simple trick to know which one to use is to decide who you are talking to, or if you are talking to anyone at all!

“Tell” is specific, in that you must say WHO you told the information to. For example:

“I told Ana that we could meet at 17:00” (correct)
“I told that we could meet at 17:00” (incorrect because you must mention WHO you told)

“Say” is more flexible and could be used like so:
“I said we could meet at 17:00”
“I said to Ana that we could meet at 17:00” (both correct)

You can use “say” and not be talking to anyone in particular:
With “say” it’s not necessary to mention who the information was imparted to.

We hope this is helpful, and happy learning to all!