After submitting your application, USCIS must process it. Processing times vary a lot. Sometimes it can take 12-18 months for the U Visa to be processed and approved. If you are required to submit extra evidence to USCIS, it might take longer.
10,000 U Visas are granted every year. This is no limit to the amount of U Visas for spouses and other eligible family members of crime victims. If 10,000 U Visas have already been granted when you apply, USCIS creates a waiting list for eligible applicants.
If you are on the waiting list, you can’t be deported and will be eligible to apply for work authorization. People on the waiting list receive their visas in the order in which they were received.