Service Level Agreement - a commitment between service provider and customer defining expected performance and reliability. Like a warranty that promises your service will work 99.9% of the time or you get compensation.
Cloud providers offer SLAs guaranteeing 99.99% uptime, meaning your application should only be down for about 4 minutes per month maximum.
SLAs are not specific services but contractual agreements offered by all major cloud providers to ensure service reliability and performance.