South will pass, vulnerable, though some experts might try a weak 2♥ s (6/4 bid more).

West will bid 1♣ the lower of two 4 card suits.

North will pass.

East will bid 1♠.

West will probably bid 2NT to show balanced 18HCPs.

East knows they have a minimum of 18+18HCPs=36, so 6NT will be good, but is there a possibility of 7NT.

One possibility is to bid 5NT quantitative slam invite (similar to the more common NT - 4NT asking to bid 6 if maximum). What is maximum? The main thing is a source of tricks, so solid 5 or 6 card suits are great). Here West has 18HCPS, some good intermdiates but poor shape. Tough call.

5NT cannot be passed - you have to bid 6 or 7NT.