If you 'come to know' something it means that you eventually learn this, after a period of time. We can use 'come to' with other verbs about knowing, such as 'He came to understand' or 'They came to realise'. By the way, there is a grammar mistake in the phrase you've given. Perhaps it should be 'She came to know' in the past?

Hi Mohammad, sometimes "she come to know", means 'she finally realized' or 'now she realizes it...'.

Really the full sentence is "can she come to know this?"

it means "start to"