What time is the meeting - for business English
It - The little word with so many uses.
The word 'it' is used to refer to a word previously mentioned in order to avoid repetition of that word.
The day was full of surprises. It had started like any other. It = the day
I find maths really difficult. It's a complete mystery to me. It = maths
I have lost my wallet. If you find it, please let me know. It = my wallet
The word 'it' can also be used to anticipate a word mentioned later in the sentence.
It's great to see you. (To see you is great.) It = to see you
It's fun playing guitar. (To play the guitar is fun.) It = playing guitar
It's difficult to know what to do. (What to do is difficult to know.) It = to know what to do
The word 'it' is used as a 'dummy' subject when talking about weather, time, distance and cost.
It's time to go home.
It's past midnight.
It's 4 miles away.