Hello Dmitrij. It's not surprising that you find these confusing because as far as meaning goes these three words mean more or less the same thing. It's more a question of how we use them, of patterns of use. So let me try to tell you about those.

With 'tell' we usually say who is told. You could say there is a personal object, so: 'Can you tell me what's happened?' We say, 'me'.

With 'say' we don't usually say who is told. So you might say 'please say each word clearly and distinctly'. And if we do say who is told, we use the word 'to', so: 'He said goodbye to me as if we would never see one another again'.

Now... There's another limit on the usage of 'tell'. We only use 'tell' to mean instruct or inform. 'I told him to wait for me on the platform'... that's an instruction. "My father used to tell me wonderful stories" - informing me.

'Say' can be used for any kind of talking. So here are three sentences where you could not use 'tell':

She said 'Where have you been?'
So I said what a good idea.
Maureen said 'What's the matter?'

We use 'tell' without a personal object in a few expressions, that are kind of fixed expressions like tell the truth, tell the time and tell the difference.

And we use 'say' before words like a word, a name, or a sentence. An example would be: 'Don't say a word.'

That's 'tell' and 'say'. You also asked about 'speak'. We use 'speak' to mean 'talk formally', and when we do use 'speak', we use the word 'to' if there's a personal object. So you could say, 'I spoke to him severely' or 'She spoke to our teachers' a__ociation last year'.

And of course we use it when we're talking about people's language ability: 'Do you speak English?' And you do, and I hope this will help you be happier with the way you speak it.

See also:
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