Off the top of my head, they want to raise corporation tax to be more in line with USA/Germany (around 30% iirc), re-instate the 50% tax rate, abandon Osborne's arbitrary deficit reduction targets/timescale (he's done this in light of Brexit), re-nationalise the railways as the contracts for the franchises lapse (and bring that forward if there are break clauses in the contracts), make universities tuition free, protect the NHS from too much private interest, bring forward shovel-ready infrastructure projects (I think they said that they will borrow for such projects, but not borrow to fund day-to-day gov. spending) build more council houses. I think that is centre-left or just left, certainly not far-left or any such nonsense.
Not renewing Trident is probably the most left-wing policy of Corbyn (but it won't necessarily be Labour policy). I'm quite ambivalent about that, though imo it makes sense not to renew it. I don't think it's an extreme policy either, I don't think the SNP are 'far-left' for having that same policy.
The way the media go on, you'd think Corbyn wants to nationalise every corner shop and have us all wearing tweed trousers or whatever.