A quick recap:
The UK referendum’d to leave the EU. On 29 March 2017 the UK invoked Article 50 of the Treaty on European Union, which governs withdrawal from the EU. A withdrawal agreement was negotiated by November last year. It was endorsed by leaders of the remaining 27 EU countries. However, it has not been ratified by UK's parliament, as May's deal was defeated twice. The speaker of the House of Commons ruled out third meaningful vote on same deal, making it necessary to postpone leaving to avoid a no-deal Brexit.
Currently, the UK's withdrawal has been postponed to April 12 if the UK doesn’t ratify the agreement by that date, and May 22 if they do.
Will the UK leave the EU without a deal by April 12th?
This question resolves positively if a no-deal Brexit occurs on or before April 12 2019 23:00 UK time. It resolves negatively if Brexit is delayed, or if a deal between the UK and the EU is reached that prevents the UK's leaving before, or on April 12. Otherwise, it resolves ambiguous.