I have the following 2 sentences:
“what Pablo said can give you a hint”
“what Pablo said could give you a hint”
Are they both correct? if no, which one and why?
Thank you very much
Usually it is clear from the context what is the difference between ‘can’ and ‘could’, but use of can can also express possibility (rather than ability).
Taking into account your examples , I think that:
‘What Pablo said can give you a hint’
emphasises that there is some form of hint hidden in Pablo’s statement,
‘What Pablo said could give you a hint’
comes with more of a neutral tone, implying that what Pablo said may or may not have hints embedded.
‘What Pablo said could give you a hint’ contains more personal involvement and subjectivity; ‘What Pablo said can give you a hint’ is more factual and objective.
Similarly, ‘How could I improve my English?’ is more a request for advice, whereas ‘How can I improve my English?’ is more a factual question about available options. (But of course we can also answer this question by giving advice.)