The phrase "staff shortages" means there is not enough employees to do the work that needs to be done. It indicates a situation where there are fewer workers available than what is necessary for a particular job or task. Full definition
A restricted regime has been put in operation as a result of staff shortages, meaning boys are spending more and more time in their cells. (politics.co.uk)
Don't forget that there are huge staff shortages in some areas, including in child protection and elderly care. (politics.co.uk)
Served as sole tier 2 desk - side support for 1400 users during staff shortage, closing approximately 60 service tickets per week. (resumehacking.com)